Answer: B. This is sometimes true.
Step-by-step explanation:
A positive correlation between 2 variables means that they generally move in the same direction meaning that as one variable rises, the other rises as well and as the other falls, the other falls as well.
However, the correlation can be strong, weak or anything in-between. This means that just because one variable increases by 12 does not mean the other would as well. It could increase by 1 alone and still have a positive correlation albeit a small one.
Therefore, if the value of one variable is above the mean, it doesn't always follow that the other with a positive correlation will as well as they just might not have that strong a correlation.
E
Homework: Practice
Exam 3
Question 7
Find the standard deviation for the group of data items.
14, 15, 16, 16, 17, 18
The standard deviation is
(Simplify your answer. Round to two decimal places as needed.)
9
Answer:
Step-by-step explanation:
Let f (x)
sinx cosx, then f'(x) =
A. Cos2x
B. sin2x
C. tan 2x
D. cos2x - sin2x
Answer:
A. Cos2x
Step-by-step explanation:
f(x) = sin(x)cos(x) = (1/2) sin(2x) using double angle formula.
f'(x) = ( (1/2)sin(2x) )' = 2(1/2)cos(2x) = cos(2x)
PLEASE HELP FAST!! The cone and the cylinder below have equal surface area. True or False??
Answer:
B. FALSE
Step-by-step explanation:
Surface area of cone = πr(r + l)
Where,
r = r
l = 3r
S.A of cone = πr(r + 3r)
= πr² + 3πr²
S.A of cone = 4πr²
Surface area of cylinder = 2πrh + 2πr² = 2πr(h + r)
Where,
r = r
h = 2r
S.A of cylinder = 2πr(2r + r)
= 4πr² + 2πr²
S.A of cylinder = 6πr²
The surface are of the cone and that of the cylinder are not the same. The answer is false.
Answer:false
Step-by-step explanation:
False
What is the distance between the coordinates (4,2) and (0,2)
Answer: Hi!
The distance between the coordinates (4,2) and (0,2) is 4 units.
The coordinates have the same location on the y axis, but the coordinates have different locations on the x axis. (4,2) is 4 units to the right of the x axis and 2 up on the y axis, while (0,2) goes just straight up to 2 on the y axis. If we graphed these, the two points would be aligned with each other, but a distance of 4 units would separate them horizontally.
Hope this helps!
A tank is filled at a constant rate. 10 minutes after filling is started, the tank contains 4.8L of water. After 35 minutes the tank contains 7.3L of water.
a. Find the rate at which the tank is being filled?
b. Find the initial volume of fluid in the tank and express it as a function in terms of V and t.
c. Find how long it takes to filled, if the tank has a maximum capacity of 60L?
Answer:
Part A)
0.1 liters per minute.
Part B)
There was initially 3.8 liters of water.
[tex]\displaystyle V(t) = 0.1(t - 10) + 4.8[/tex]
Part C)
562 minutes.
Step-by-step explanation:
A tank is filled at a constant rate. After 10 minutes, the tank contains 4.8 L of water and after 35 minutes, the tank contains 7.3 L of water.
Part A)
We can represent the current data with two points: (10, 4.8) and (35, 7.3). The x-coordinate is measured in minutes since the tank began to be filled and the y-coordinate is measured in how full the tank is in liters.
To find the rate at which the tank is being filled, find the slope between the two points:
[tex]\displaystyle m = \frac{\Delta y}{\Delta x} = \frac{(7.3)-(4.8)}{(35)-(10)} = \frac{2.5}{25} = 0.1[/tex]
In other words, the rate at which the tank is being filled is 0.1 liters per minute.
Part B)
To find the function of the volume of the tank, we can use the point-slope form to first find its equation:
[tex]\displaystyle y - y_1 = m( x - x_1)[/tex]
Where m is the slope/rate of change and (x₁, y₁) is a point.
We will substitute 0.1 for m and let (10, 4.8) be the point. Hence:
[tex]\displaystyle y - (4.8) = 0.1(x - 10)[/tex]
Simplify:
[tex]\displaystyle y = 0.1(x-10) + 4.8[/tex]
Since y represent how full the tank is and x represent the time in minutes since the tank began to be filled, we can substitute y for V(t) and x for t. Thus, our function is:
[tex]\displaystyle V(t) = 0.1(t - 10) + 4.8[/tex]
The initial volume is when t = 0. Evaluate:
[tex]\displaystyle V(0) = 0.1 ((0) - 10) + 4.8 = 3.8[/tex]
There was initially 3.8 liters of water.
Part C)
To find how long it will take for the tank to be completely filled given its maximum capacity of 60 liters, we can let V(t) = 60 and solve for t. Hence:
[tex]60 = 0.1(t - 10) + 4.8[/tex]
Subtract:
[tex]55.2 = 0.1(t - 10)[/tex]
Divide:
[tex]552 = t - 10[/tex]
Add. Therefore:
[tex]t = 562\text{ minutes}[/tex]
It will take 562 minutes for the tank to be completely filled.
Gabrielle's age is two times Mikhail's age. The sum of their ages is 30 . What is Mikhail's age?
Step-by-step explanation:
G=2m
m+G=30
m +2m =30
3m=30
m=10
An architect was designing a rectangular room with a length of 16 feet, a width of 14 feet,
and a height of 10 feet.
What is the volume, in cubic feet of the room?
Show your work
cubic feet
Answer
The architect changed his design and added 2 feet to the length and width of the room.
In cubic feet, how much greater is the volume of the room in his new design?
Show your work
cubic feet
Answer
Hurrryyy knowww
Answer:
(1) 16 x 14 x 10 Room: 2240 ft^3.
(2) How much greater the 18 x 16 x 10 Room is: 640 ft^3.
Step-by-step explanation:
To find the volume of a given space, all we need to do is multiply length*width*height. In this case, the values are 16*14*10, which equals 2240 ft^3.
The changed design would have a volume of 18*16*10, which would equal 2880 ft^3.
To find the difference in volume between the two rooms, all we have to do is subtract the smaller room from the bigger room. 2880 - 2240 = 640 ft^3.
Alex has to pay his car insurance twice a year. Each Payment is 312. How much money should Alex budget for his insurance each month?
Answer:
$52
Step-by-step explanation:
$52. Since Alex pays for car insurance twice a year, divide the cost of each payment by 6, the number of months in half a year. This will tell you how much money Alex needs to set aside each month to cover his insurance costs.
312÷6=52
HELP ASAP
The figure shows two parallel lines AB and DE cut by the transversals AE and BD.
Which best explains the relationship between triangle ABC and triangle EDC?
Answer
its the first one
Step-by-step explanation:
Find the area of the figure. (Sides meet at right angles.)
Answer:
56
Step-by-step explanation:
A=(3*4)+(4*(4+3+4))=56
Which equation best describes the graph.
Answer:
A. [tex]y=4x-5[/tex]
Step-by-step explanation:
The equations are in slope-intercept form, which is written as y=mx+b. Where m is the slope and b is the y-intercept. So, first, find the slope. The line increases by 4 every unit; this means the slope is 4. Then, find the y-intercept. The y-intercept is where the line crosses the y-axis. Since the line crosses at -5, that is the b value. Therefore, the final answer is y=4x-5.
If the function Q(t)=4e-0.00938t models the quantity (in kg) of an element in a storage unit after t years, how long will it be before the quantity is less than 1.5kg? Round to the nearest year.
Answer:
105 years
Step-by-step explanation:
Given the function :
Q(t) = 4e^(-0.00938t)
Q = Quantity in kilogram of an element in a storage unit after t years
how long will it be before the quantity is less than 1.5kg
Inputting Q = 1.5kg into the equation:
1.5 = 4e^(-0.00938t)
Divide both sides by 4
(1.5 / 4) = (4e^(-0.00938t) / 4)
0.375 = e^(-0.00938t)
Take the ln of both sides
In(0.375) = In(e^(-0.00938t))
−0.980829 = -0.00938t
Divide both sides by 0.00938
0.00938t / 0.00938 = 0.980829 /0.00938
t = 104.56599
When t = 104.56599 years , the quantity in kilogram of the element in storage will be exactly 1.5kg
Therefore, when t = 105 years, the quantity of element in storage will be less than 1.5kg
Find the value of x.
A. 65
B. 32.5
C. 118
D. 130
Answer:
D. 130
Step-by-step explanation:
The lines are tangent to the circle therefore 90º which makes 65º + 25º. The small triangle with C is iso so the angle of C would be 130 and equivalent to x
Answer:
[tex]D.\ \ 130[/tex]
Step-by-step explanation:
1. Approach
Refer to the attached diagram of the figure for further explanation. In this problem, one is asked to solve for the degree measure of arc (x). The easiest method to do so is to use the triangle (CAB). One can solve for the measure of angle (<CBA) by using the tangent to radius theorem. Then one can solve for the measure of angle (CAB) by using the base angles theorem. Then one can use the sum of angles in a triangle theorem to solve for angle (<BCA). Finally, one can use the central angles theorem to solve for the arc (x).
2. Find the measure of angles in the triangle
A. Find the measure of angle (<CBE)
As per the given image, lines (BE) and (AE) are tangent. This means that they intersect the circle at exactly one point. A radius is the distance from the center of a circle to the circumference or outer edge of a circle. All radii in a single circle are congruent. The radius of tangent theorem states that, when a tangent intersects a circle at a point of tangency, and a radius also intersects the point of tangency, the angle between the radius and the tangent is a right angle. One can apply this here by stating the following:
[tex]m<CBE = 90[/tex]
Express angle (<CBE) as the sum of two other angles:
[tex]m<CBE = m<CBA + m<ABE[/tex]
Substitute with the given and found information:
[tex]m<CBE = m<CBA + m<ABE[/tex]
[tex]90 = m<CBA + 65[/tex]
Inverse operations,
[tex]90 = m<CBA + 65[/tex]
[tex]25= m<CBA[/tex]
B. FInd the measure of angle (<CAB)
As stated above all radii in a single circle are congruent. This means that lines (CB) and (CA) are equal. Therefore, the triangle (CAB) is an isosceles triangle. One property of an isosceles triangle is the base angles theorem, this theorem states that the angles opposite the congruent sides of an isosceles triangle are congruent. Applying this theorem to the given problem, one can state the following:
[tex]m<CBA = m<CAB = 25[/tex]
C. Find the measure of angle (<ACB)
The sum of angles in any triangle is (180) degrees. One can apply this theorem here to the given triangle by adding up all of the angles and setting the result equal to (180) degrees. This is shown in the following equation:
[tex]m<CAB + m<CBA + m<ACB = 180[/tex]
Substitute,
[tex]m<CAB + m<CBA + m<ACB = 180[/tex]
[tex]25 + 25 + m<ACB = 180[/tex]
Simplify,
[tex]25 + 25 + m<ACB = 180[/tex]
[tex]50 + m<ACB = 180[/tex]
Inverse operations,
[tex]50 + m<ACB = 180[/tex]
[tex]m<ACB = 130[/tex]
3. Find the measure of arc (x)
The central angles theorem states that when an angle has its vertex on the center of the circle, its angle measure is equivalent to the measure of the surrounding arc. Thus, one apply this theorem here by stating the following:
[tex]m<ACB = (x)\\130 = x[/tex]
point estimate A sample of 81 observations is taken from a normal population with a standard deviation of 5. The sample mean is 40. Determine the 95% confidence interval for the population mean
Answer:
The 95 percent Confidence Interval is for the population is (38.911 , 41.089)
Step-by-step explanation:
To solve the above question, we would be making use of the confidence interval formula:
Confidence Interval = Mean ± z score × σ/√n
In the above question,
Mean = 40
σ = Standard deviation = 5
n = number of samples = 81
Confidence Interval = 95%
The z score for a 95% confidence interval = 1.96
Therefore, the confidence interval =
= 40 ± 1.96 (5/√81)
= 40 ± 1.96(5/9)
= 40 ± 1.0888888889
Confidence Interval
a)40 + 1.0888888889
= 41.0888888889
Approximately = 41.089
b ) 40 - 1.0888888889
= 38.911111111
Approximately = 38.911
Therefore, the 95 percent Confidence Interval is for the population is (38.911 , 41.089)
Express the product of z1 and z2 in standard form given that [tex]z_{1} = -3[cos(\frac{-\pi }{4} )+isin(\frac{-\pi }{4} )][/tex] and [tex]z_{2} = 2\sqrt{2} [cos(\frac{-\pi }{2} )+isin(\frac{-\pi }{2} )][/tex]
Answer:
Solution : 6 + 6i
Step-by-step explanation:
[tex]-3\left[\cos \left(\frac{-\pi }{4})\right+i\sin \left(\frac{-\pi }{4}\right)\right]\cdot \:2\sqrt{2}\left[\cos \left(\frac{-\pi }{2}\right)+i\sin \left(\frac{-\pi }{2}\right)\right][/tex]
This is the expression we have to solve for. Now normally we could directly apply trivial identities and convert this into standard complex form, but as the expression is too large, it would be easier to convert into trigonometric form first ----- ( 1 )
( Multiply both expressions )
[tex]-6\sqrt{2}\left[\cos \left(\frac{-\pi }{4}+\frac{-\pi \:\:\:}{2}\right)+i\sin \left(\frac{-\pi \:}{4}+\frac{-\pi \:\:}{2}\right)\right][/tex]
( Simplify [tex]\left(\frac{-\pi }{4}+\frac{-\pi }{2}\right)[/tex] for both [tex]\cos \left(\frac{-\pi }{4}+\frac{-\pi }{2}\right)[/tex] and [tex]i\sin \left(\frac{-\pi }{4}+\frac{-\pi }{2}\right)[/tex] )
[tex]\left(\frac{-\pi }{4}+\frac{-\pi }{2}\right)[/tex] = [tex]\left(-\frac{3\pi }{4}\right)[/tex]
( Substitute )
[tex]-6\sqrt{2}\left(\cos \left(-\frac{3\pi }{4}\right)+i\sin \left(-\frac{3\pi }{4}\right)\right)[/tex]
Now that we have this in trigonometric form, let's convert into standard form by applying the following identities ----- ( 2 )
sin(π / 4) = √2 / 2 = cos(π / 4)
( Substitute )
[tex]-6\sqrt{2}\left(-\sqrt{2} / 2 -i\sqrt{2} / 2 )[/tex]
= [tex]-6\sqrt{2}\left(-\frac{\sqrt{2}}{2}-\frac{\sqrt{2}}{2}i\right)[/tex] = [tex]-\frac{\left(-\sqrt{2}-\sqrt{2}i\right)\cdot \:6\sqrt{2}}{2}[/tex]
= [tex]-3\sqrt{2}\left(-\sqrt{2}-\sqrt{2}i\right)[/tex] = [tex]-3\sqrt{2}\left(-\sqrt{2}\right)-\left(-3\sqrt{2}\right)\sqrt{2}i[/tex]
= [tex]3\sqrt{2}\sqrt{2}+3\sqrt{2}\sqrt{2}i:\quad 6+6i[/tex] - Therefore our solution is option a.
It is known that 80% of all brand A external hard drives work in a satisfactory manner throughout the warranty period (are "successes"). Suppose that n= 15 drives are randomly selected. Let X = the number of successes in the sample. The statistic X/n is the sample proportion (fraction) of successes. Obtain the sampling distribution of this statistic.
Answer:
P (x= 5) = 0.0001
P(x=3) = 0.008699
Step-by-step explanation:
This is a binomial distribution .
Here p = 0.8 q= 1-p = 1-0.8 = 0.2
n= 15
So we find the probability for x taking different values from 0 - 15.
The formula used will be
n Cx p^x q^n-x
Suppose we want to find the value of x= 5
P (x= 5) = 15C5*(0.2)^10*(0.8)^5 = 0.0001
P(x=3) = 15C3*(0.2)^12*(0.8)^3 = 9.54 e ^-7= 0.008699
Similarly we can find the values for all the trials from 0 -15 by substituting the values of x =0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15.
The value for p(x = 5) is 0.0001 and the value for p(x = 3) is 0.008699.
It is given that the 80% of all brand A external hard drives work in a satisfactory manner throughout the warranty period.
It is required to find the sampling distribution if n =15 samples.
What is sampling distribution?It is defined as the probability distribution for the definite sample size the sample is the random data.
We have p =80% = 0.8 and q = 1 - p ⇒ 1 -0.8 ⇒ 0.2
n = 15
We can find the probability for the given x by taking different values from 0 to 15
the formula can be used:
[tex]\rm _{n}^{}\textrm{C}_x p^xq^{n-x}[/tex]
If we find the value for p(x = 5)
[tex]\rm _{15}^{}\textrm{C}_5 p^5q^{15-5}\\\\\rm _{15}^{}\textrm{C}_5 0.8^50.2^{10}[/tex]⇒ 0.0001
If we find the value for p(x = 3)
[tex]\rm _{15}^{}\textrm{C}_3 0.8^30.2^{12}\\[/tex] ⇒
Similarly, we can find the values for all the trials from 0 to 15 by putting the values of x = 0 to 15.
Thus, the value for p(x = 5) is 0.0001 and the value for p(x = 3) is 0.008699.
Learn more about the sampling distribution here:
https://brainly.com/question/10554762
Apply the distributive property to factor out the greatest common factor. 18d+12 =18d+12=18, d, plus, 12, equals
Answer:
[tex]\huge\boxed{6 ( 3d + 2 )}[/tex]
Step-by-step explanation:
18d + 12
The greatest common factor is 6, So we need to factor out 6
=> 6 ( 3d + 2 ) [Distributive property has been applied and this is the simplest form]
Answer:
6(3d+2)
Step-by-step explanation:
6 is the gcd of the two terms.
Dan weighs 205 pounds but is only 5 feet 8 inches tall. Evan is 6 feet tall. How much would you expect Evan to weigh if they have the same height/weight ratio? WILL MARK BRAINLIST
Answer:
217.0588235294118
Step-by-step explanation:
Convert all height to inches.
5' 8" = 68 inches
6' = 72
205/68 = 3.014705882352941
Height/Weight Ratio * Evan's Height = 217.0588235294118
Which group of numbers is ordered from LEAST to GREATEST?
Select one:
A.
246,263, 250,100, 250,000
B.
250,100, 246,263, 250,000,
C.
246,263, 250,000, 250,100,
D.
250,100, 250,000, 246,263,
I don't understand word problems can someone please answer it for me and I need it ASAP.
Answer:
Inequality: 3 + 1.2c
What you'd put on graph: 1 ≥ 13.50
Help us plazz this is mathematics IGCSE fast as you can
Answer:
Step-by-step explanation:
y varies direcrtly with √(x+5) wich can be expressed mathematically as:
● y = k*√(x+5)
Let's calculate k khowing that y=4 and x=-1
● 4 = k*√(-1+5)
● 4 = k*√(4)
● 4 = k * 2
● k = 4/2
● k = 2
■■■■■■■■■■■■■■■■■■■■■■■■■■
Let's calculate y khowing that x = 11
● y = k*√(x+5)
● y = 2×√(11+5)
● y = 2× √(16)
● y = 2× 4
● y = 8
Answer:
The value of y is 8.
Step-by-step explanation:
Given that y is directly proportional to √(x+5) so the equation is y = k√(x+5) where k is constant. First, you have to find the value of k with given values :
[tex]y = k \sqrt{x + 5} [/tex]
[tex]let \: x = - 1,y = 4[/tex]
[tex]4 = k \sqrt{ - 1 + 5} [/tex]
[tex]4 = k \sqrt{4} [/tex]
[tex]4 = k(2)[/tex]
[tex]4 \div 2 = k[/tex]
[tex]k = 2[/tex]
So the equation is y = 2√(x+5). In order to find the value of y, you have to substitute x = 11 into the equation :
[tex]y = 2 \sqrt{x + 5} [/tex]
[tex]let \: x = 11[/tex]
[tex]y = 2 \sqrt{11 + 5} [/tex]
[tex]y = 2 \sqrt{16} [/tex]
[tex]y = 2(4)[/tex]
[tex]y = 8[/tex]
-3x^5y^7/6xy^8
PLEASE HELP
9514 1404 393
Answer:
-x^4/(2y)
Step-by-step explanation:
Perhaps you want to simplify ...
[tex]-\dfrac{3x^5y^7}{6xy^8}=-\dfrac{3}{6}x^{5-1}y^{7-8}=-\dfrac{x^4y^{-1}}{2}=\boxed{-\dfrac{x^4}{2y}}[/tex]
__
The applicable rules of exponents are ...
(a^b)/(a^c) = a^(b-c)
a^-b = 1/a^b
_____
Comment on notation
When writing a fraction in plain text, any denominator that includes an arithmetic operation must be enclosed in parentheses. Your given expression is properly written as ...
-3x^5y/(6xy^8)
Without the parentheses, the product xy^8 is in the numerator. This is demanded by the order of operations, which requires you evaluate your expression as (-3x^5y^7/6)·xy^8
Three out of every ten dentists recommend a certain brand of fluoride toothpaste. Which assignment of random digits would be used to simulate the random sampling of dentists who prefer this fluoride toothpaste?
Answer:
eddfdgdccggģdffcdrrfxddxcvgfx
solve for x please help ! (show work)
Answer:
x = -5
Step-by-step explanation:
-(5x-2) = 27
Distribute the minus sign
-5x +2 = 27
Subtract 2 from each side
-5x +2-2 = 27-2
-5x = 25
Divide by -5
-5x/-5 = 25/-5
x = -5
Answer:
X=-5
Step-by-step explanation:
-(5x-2)=27
-5x+2=27
-5x=27-2
-5x=25
x=25/-5
=-5
Rawen buys 5 1/4 yards of fabric. Zoey buys 2/3 as much fabric as Rawen does. How much fabric does Zoey buy?
Answer:
3.5 yards of fabric
Step-by-step explanation:
Find 2/3 of 5 1/4:
5 1/4(2/3)
= 3.5 yards of fabric
12. Consider the function ƒ(x) = x^4 – x^3 + 2x^2 – 2x. How many real roots does it have?
options:
A) 2
B) 1
C) 3
D) 4
Answer:
Step-by-step explanation:
Hello, let's factorise as much as we can.
[tex]x^4-x^3 + 2x^2-2x\\\\=x(x^3-x^2+2x-2)\\\\=x(x-1)(x^2+2)[/tex]
So, the solutions are
[tex]0, \ 1, \ \sqrt{2}\cdot i, \ -\sqrt{2}\cdot i[/tex]
There are only 2 real roots.
Thank you.
Answer:
So, the solutions are
There are only 2 real roots.
Step-by-step explanation:
What is the value of x that makes l1||l2?
A. 15
B. 25
C. 18
D. 29
Answer:
x = 29
Step-by-step explanation:
The angles are corresponding angles and corresponding angles are equal when the lines are parallel
3x+17 = 4x-12
Subtract 3x from each side
3x+17-3x = 4x-12-3x
17 = x-12
Add 12 to each side
17+12 = x-12+12
29 =x
Answer:
D. 29
Step-by-step explanation:
If you plug in 29 in the missing values for L1 and L2, you get
L1 = 3(29) + 17 = 104
L2 = 4(29) - 12 = 104
I know I am correct because since both L1 and L2 are parallel and T in cutting them, I know that they are both going to be the same degrees, 104.
So, your answer would be D. 29
Hope the helps! :)
Will give brainliest. A farmer is painting a new barn. He will need to calculate the surface area of the barn to purchase the correct amount of paint. In which of the following units can the farmer expect to calculate the surface area? yd2 yd m3 m
Answer:
yd^2
Step-by-step explanation:
I took the test :)
The farmer calculate surface area in unit of [tex]yd^{2}[/tex]
Surface area :The surface area of any given object is the area or region occupied by the surface of the object.
Volume is the amount of space available in an object. Each shape has its surface area as well as volume.Surface area is the total area of the faces of a three-dimensional shape. Surface area is measured in square units.Thus , The farmer calculate surface area in unit of [tex]yd^{2}[/tex]
Learn more about the surface area here:
https://brainly.com/question/16519513
An empty swimming pool is to be filled to the top. The pool is shaped like a rectangular prism with length 10m, width 8m , and depth 4m. Suppose water is pumped into the pool at a rate of 16m cubed per hour. How many hours does it take to fill the empty pool?
Answer:
20 hours
Step-by-step explanation:
10*8*4=320 (volume of the pool)
320/16=20 hours
Answer:
20 hours
Step-by-step explanation:
10x8x4 = 320
320 / 16 = 20
it takes 20 hours to fill the empty pool
A librarian needs to package up all of the children's books and move them to a different location in the library. There are 625 books, and she can fit 25 books in one box. How many boxes does she need in order to move all of the books? 5 B. 25 C. 125 D. 600 E. 650
Answer: B. 25
Step-by-step explanation:
Given: Total books = 625
Number of books can fit in one box = 25
Now, the number of boxes she need to move all of the books = (Total books) ÷ (Number of books can fit in one box )
= 625÷25
= 25
hence, she requires 25 boxes in order to move all of the books.
So, correct option is B. 25.