On a multiple choice test with 24 questions each question has four possible answers one of which is correct for students who guess at all answers find the variance for the number of correct answers

Answers

Answer 1

Answer:

The variance for the number of correct answers is 4.5.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the correct answer is guessed, or it is not. Questions are independent of each other, so we use the binomial probability distribution to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

The variance of the binomial distribution is:

[tex]V(X) = np(1-p)[/tex]

24 questions

This means that [tex]n = 24[/tex]

Each question has four possible answers one of which is correct

This means that [tex]p = \frac{1}{4} = 0.25[/tex]

Find the variance for the number of correct answers

[tex]V(X) = np(1-p) = 24*0.25*0.75 = 4.5[/tex]

The variance for the number of correct answers is 4.5.


Related Questions

The mean of 100 numerical observations is 51.82 what is the value of all 100 numbers

Answers

Answer: 5182

To get the value of all 100 numbers you would need to multiply.

Step-by-step explanation:

51.82x100= 5182

Sandy can fold 6 towels in 3 minutes. If she continues at this rate, how many minutes will it take her to fold 36 towels?

Answers

Hey there! :)

Answer:

x = 18 minutes.

Step-by-step explanation:

To solve this equation, set up a ratio.

# of towels over time taken:

[tex]\frac{6}{3} = \frac{36}{x}[/tex]

Cross multiply:

6x = 108

Divide both sides by 6:

6x/6 = 108/6

x = 18 minutes.

Answer:

In eighteen minutes she will have folded all 36

Find the value of x that makes A||B

Answers

Answer:

For lines A and B to be parallel, the Same Side Interior angles must be supplementary which means:

2x + 10 + 4x + 80 = 180

6x + 90 = 180

6x = 90

x = 15°

What is the solution to this inequality -13x> - 39

Answers

Answer:

Isolate the variable by dividing each side by factors that don't contain the variable.

Inequality Form:  x < 3

Interval Notation:

( − ∞ , 3 )

Answer:

x<3

Step-by-step explanation:

-13x>-39

-13x>-39 (Divided by Negative Thirteen)

-13>-13

x<3 (The great sign changes to less than when divided or multiplied by a negative number.)

x={...0,1,2}

Hope this helps ❤

A surveyor is trying to find the height of a hill. He/she takes a ‘sight’ on the top of the hill and find that the angle of elevation is 40°. He/she move a distance of 150 metres on level ground directly away from the hill and takes a second ‘sight’. From this point, the angle of elevation is 22°. Find the height of the hill, correct to 1 d.p.

Answers

Answer:

The height of the hill is 116.9 meters.

Step-by-step explanation:

The diagram depicting this problem is drawn and attached below.

From Triangle ABC

[tex]\tan 22^\circ=\dfrac{h}{150+x}\\\\h=\tan 22^\circ(150+x)[/tex]

From Triangle XBC

[tex]\tan 40^\circ =\dfrac{h}{x}\\\\h=x\tan 40^\circ[/tex]

Therefore:

[tex]h=\tan 22^\circ(150+x)=x\tan 40^\circ\\150\tan 22^\circ+x\tan 22^\circ=x\tan 40^\circ\\x\tan 40^\circ-x\tan 22^\circ=150\tan 22^\circ\\x(\tan 40^\circ-\tan 22^\circ)=150\tan 22^\circ\\x=\dfrac{150\tan 22^\circ}{\tan 40^\circ-\tan 22^\circ} \\\\x=139.30[/tex]

Therefore, the height of the hill

[tex]h=139.3\times \tan 40^\circ\\=116.9$ meters( correct to 1 d.p.)[/tex]

The height of the hill is 116.9 meters.

a bag contains only red and blue counters the probability that a counter is blue is 0.58 A counter is picked at random What is the probability that it is red

Answers

Answer:

0.42

Process:

1 - 0.58

0.42

1) Which statement contains an exact number? A) A gross of paper contains 144 sheets. B) One sheet of paper is 0.0042 inches thick. C) One sheet of paper measures 8.5 x 11 inches. D) A ream of medium weight paper weighs 20 pounds. Answer: A

Answers

Answer:

B) One sheet of paper is 0.0042 inches thick

Step-by-step explanation:

All the other values are not give from just a sheet of paper, and/or they are either a cumulative value, or values that will be used to calculate another value

Only option B defines a value for a unit of paper, and the value is definite.

Option A indicates  the number in a group (gross)

Option C shows two values that can be used to calculate one value; the area.

Option D indicates an accumulated value of weight.

what is the the square route of 98985947875875847688748687587865758 add 9547589777778747 to the answer.

Answers

Answer:

800090908988

Step-by-step explanation:

Answer = 8000090908988

A ship traveled at an average rate of 25 miles per hour going west. It then traveled at an average rate of 19 miles per hour heading north. If the ship traveled a total of 145 miles in 7 hours, how many miles were traveled heading west?

Answers

Answer:

50 miles

Step-by-step explanation:

hello,

let's note x the number of miles travelled heading west,

it takes 1 hour to travel 25 miles

so it takes x/25 hours to travel x miles

we know that in total it travels 7 hours so it will travel 7-x/25 hours heading North, then heading North it takes 1 hour to travel 19 miles

so in 7-x/25 hours it travels 19(7-x/25) miles

we can write, as the total distance is 145 miles

[tex]x+19(7-\dfrac{x}{25})=145\\<=> 25x+3325-19x=3625\\<=> 6x=300\\<=> x = 50[/tex]

we can verify

50 miles heading West takes 2 hours

in 5 hours it travels 19*5 = 95 miles

the total is 145 miles

so this is correct

hope this helps

How many ways can 8 people stand in a line if Alice and Bob refuse to stand next to each other?

Answers

Answer: 30,240 different ways

====================================================

Explanation:

We have 8 people to start with. If we remove Alice and Bob, and replace them with Charlie (who will be a stand in for both people), then we have 8-2+1 = 7 people in this line. There are 7! = 7*6*5*4*3*2*1 = 5040 different permutations or line orderings for these seven people.

For any given permutation, replace Charlie with Alice and Bob. There are two ways to do this for any ordering. We could have Alice in front of Bob, or Bob in front of Alice. So there are 2 times as many permutations compared to 5040. In other words, there are 2*5040 = 10,080 different permutations where Alice and Bob are standing together.

This is out of 8! = 8*7*6*5*4*3*2*1 = 40,320 different permutations overall of arranging 8 people in a line.

This means there are 40,320 - 10,080 = 30,240 different ways to arrange 8 people such that Alice and Bob are not standing together.

In summary, the idea is to find out how many ways there are to have Alice and Bob together. Then we subtract that result from the total number of ways to arrange 8 people to get our final answer.

Answer:

30240 got it from a teacher :>

Step-by-step explanation:

RSM XD

3) BRAINLIEST & 10 + POINTS! :)

Answers

Answer:

33,175.21/radians/sec

Step-by-step explanation:

22 rev/sec x 60sec/1 min x 4ft x2 pi/1 rev

22 x 60 = 1320

1320 x 4 = 5280

2 x pi = 6.2831853072

5280 x 6.2831853072= 33,175.218421884

There is no overlap between the graphs of y< x+ 2 and y> x-2.
True or False

Someone help please

Answers

Answer:I think it's TRUE not sure

Step-by-step explanation:

Help me plzzzzz!!!!

Answers

Answer:124

Step-by-step explanation:

2x + 8 + x - 2 = 180

Add like terms

3x + 6 = 180

Subtract the 6 from both sides

3x + 6 - 6 = 180 - 6

3x = 174

Divide by 3

x = 58

Now we have to find the measure of angle ACD

2(58) + 8 = 124

What are the angle measurements of 1,2,3 & 4 for #3 & the measurements for 1 &2 on #4?

Answers

Step-by-step explanation:

iii=90

41+i=90(opposite angle)

i=90-41

i=49

26+ii+49+41=180(straight line angle)

116+ii=180

ii=180-116

ii=64

50+25+iv=26+64(opposite angle)

75+iv=90

iv=90-75

iv=15

55+i+55=180(straight line angle)

110+i=180

i=180-110

i=70

ii=55(alternative angle)

please help me with this

Answers

Answer:

Volume = 160 cm³   (Unit = cm³)

Step-by-step explanation:

Length = 4 cm

Width = 4 cm  (Because it's a square based cuboid!)

Height = 10 cm

Now, Volume:

Volume = [tex]Length * Width*Height[/tex]

Volume = 4 * 4 * 10

Volume = 160 cm³

Answer:

160 cm³

Step-by-step explanation:

The base is a square. The side length of the base is 4 cm.

The volume of a square-based cuboid is the area of square × height or length.

4² × 10

16 × 10

= 160

The volume of the square-based cuboid is 160 cm³.

What is the solution to the equation below? Round your answer to two decimal places. 4+4•log2 x=4

Answers

Answer:

Option (C)

Step-by-step explanation:

Given expression is,

[tex]4+4\times \text{log}_2(x)=14[/tex]

By subtracting 4 from both the sides of the equation.

[tex]4\times \text{log}_2(x)=14-4[/tex]

Now divide the equation by 4

[tex]\text{log}_2(x)=\frac{10}{4}[/tex]

[tex]\text{log}_2(x)=2.5[/tex]

[If [tex]\text{log}_ab=x[/tex] , then [tex]b=a^{x}[/tex]]

[tex]x=(2)^{2.5}[/tex]

[tex]x = 5.657[/tex]

x ≈ 5.66

Therefore, Option C will be the correct option.

4+4•log2 x=14

x= 5.66


A caterer receives an order for 25 sandwiches, 1 gallon of soup and 3 dozen cookies.
His food cost equals 28% and his labor and miscellaneous costs is 32%. What
percentage is his profit margin? a. 17%
b. 40%
c. 33%
d. 51%​

Answers

Answer:

b. 40%

Step-by-step explanation:

The price he sells at is 100%.

His costs are 28% and 32%.

Total costs = 28% + 32% = 60%

His profit is

100% - 60% = 40%

Answer: b. 40%

Today, the waves are crashing onto the beach every 4.8 seconds. The times from when a person arrives at the shoreline until a crashing wave is observed follows a Uniform distribution from 0 to 4.8 seconds. 61% of the time a person will wait at least how long before the wave crashes in?

Answers

Answer:

61% of the time a person will wait at least 1.872 seconds before the wave crashes in.

Step-by-step explanation:

An uniform probability is a case of probability in which each outcome is equally as likely.

For this situation, we have a lower limit of the distribution that we call a and an upper limit that we call b.

The probability that we find a value X lower than x is given by the following formula.

[tex]P(X \leq x) = \frac{x - a}{b-a}[/tex]

Uniform distribution from 0 to 4.8 seconds.

This means that [tex]a = 0, b = 4.8[/tex]

61% of the time a person will wait at least how long before the wave crashes in?

This is the 100 - 61 = 39% percentile, which is x for which [tex]P(X \leq x) = 0.39[/tex]. So

[tex]P(X \leq x) = \frac{x - a}{b-a}[/tex]

[tex]0.39 = \frac{x - 0}{4.8 - 0}[/tex]

[tex]x = 4.8*0.39[/tex]

[tex]x = 1.872[/tex]

61% of the time a person will wait at least 1.872 seconds before the wave crashes in.

I don't know if I asked this already but: 3x+2y=11 2x-2y=14 Solve for the variables.

Answers

Answer:

x = 5, y = -2.

Step-by-step explanation:

3x+2y=11

2x-2y=14

Adding removes the y terms:

5x = 25

x = 5.

Substitute for x in the first equation:

3(5) + 2y = 11

2y = 11 - 15 = -4

y = -2.

Answer:

[tex]3x + 2y = 11and2x - 2y = 14 \\ 2 \times 3x + 2 \times 2y = 2 \times 11and3 \times 2x + 3( - 2)y = 3 \times 12 \\ 6x + 4y = 22nd6x - 6y = 42 \\ 6x - 6x + 4y + 6y = 22 - 42 \\ 4y + 6y = 22 - 42 \\ 10y = 22 - 42 \\ 10y = - 20 \\ y = - 2 \\ \\ \\ \\ 2x - 2( - 2) = 14 \\ 2x + 4 = 14 \\ 2x = 10 \\ x = 5[/tex]

[tex]\frac{5x-11}{2x^2+x-6}[/tex] You need to work for your points now!

Answers

Answer:

[tex]\frac{5x-11}{\left(2x-3\right)\left(x+2\right)}[/tex]

Step-by-step explanation:

[tex]\frac{5x-11}{2x^2+x-6}[/tex]

Factor the denominator.

[tex]\frac{5x-11}{\left(2x-3\right)\left(x+2\right)}[/tex]

The fraction cannot be simplified further.

Answer:

[tex] \frac{5x - 11}{(x + 2)(2x - 3)} [/tex]

solution,

[tex] \frac{5x - 11}{2 {x}^{2} + x - 6} \\ = \frac{5x - 11}{2 {x}^{2} + (4 - 3)x - 6} \\ = \frac{5x - 11}{2 {x}^{2} + 4x - 3x - 6 } \\ = \frac{5x - 11}{2x(x + 2) - 3(x + 2)} \\ = \frac{5x - 11}{(x + 2)(2x - 3)} [/tex]

Hope this helps..

Use the given degree of confidence and sample data to construct a confidence interval for the population proportion p.

n = 130
x = 69; 90% confidence

a. 0.463 < p < 0.599
b. 0.458 < p < 0.604
c. 0.461 < p < 0.601
d. 0.459 < p < 0.603

Answers

Answer:

d. 0.459 < p < 0.603

Step-by-step explanation:

We have to calculate a 90% confidence interval for the proportion.

The sample proportion is p=0.531.

[tex]p=X/n=69/130=0.531[/tex]

The standard error of the proportion is:

[tex]\sigma_p=\sqrt{\dfrac{p(1-p)}{n}}=\sqrt{\dfrac{0.531*0.469}{130}}\\\\\\ \sigma_p=\sqrt{0.001916}=0.044[/tex]

The critical z-value for a 90% confidence interval is z=1.645.

The margin of error (MOE) can be calculated as:

[tex]MOE=z\cdot \sigma_p=1.645 \cdot 0.044=0.072[/tex]

Then, the lower and upper bounds of the confidence interval are:

[tex]LL=p-z \cdot \sigma_p = 0.531-0.072=0.459\\\\UL=p+z \cdot \sigma_p = 0.531+0.072=0.603[/tex]

The 90% confidence interval for the population proportion is (0.459, 0.603).

Billy takes out a $2400 discounted loan using a simple interest rate of 8% for a period of 18 months. What is the effective interest rate?

Answers

Answer:

9.1

Step-by-step explanation:

To calculate the total interest payable, we use the formula

I=P0rt,

and substituting our values yields

I=$2,400×0.08×1812=$288.

Therefore the total amount he receives at loan drawdown is $2,400−$288=$2,112. To calculate the effective interest rate, we use to formula

A=P0(1+ret).

In this instance we have A=$2,400,P0=$2,112 (redefined from the value above) and t=1.5. We substitute into the formula to get

$2,400=$2,112(1+1.5re).

Solve for re.

24002112=1+1.5re

24002112−1=1.5re

24002112−11.5=re

This gives re=0.0909⋯=9.0909…%,  which is 9.1%

Pls help me I’ll mark brainLiest

Answers

Answer:y times 20 p

Step-by-step explanation:

Han and Clare are stuffing envelopes. Han can stuff 20 envelopes in one minute, and
Clare can stuff 10 envelopes in one minute. They start working together on a pile of
1,000 envelopes. How long does it take them to finish the pile?

Answers

Answer:

33 1/2 min

Step-by-step explanation:

Consider the function Upper F (x )equals StartFraction f (x )Over g (x )EndFractionF(x)= f(x) g(x) with ​g(a)equals=0. Does F necessarily have a vertical asymptote at xequals=​a? Explain your reasoning.

Answers

Answer:

No, not necessarily

Step-by-step explanation:

If g(a) = 0, it is not necessarily that F(x) will have a vertical asymptote at x = ​a

For instance, assume the following conditions:

[tex]F(x) = \frac{f(x)}{g(x)}\\f(x) = x^3*(x-a)\\g(x) = x-a[/tex]

In this conditions, g(a) = 0. F(a), however, can be written as:

[tex]F(x) = \frac{x^3*(x-a)}{x-a}\\F(a) = a^3[/tex]

In this particular case, F(x = a) does not show a vertical asymptote.

A triangle with side lengths of 4 , 5 , 6 , what are the measures of it angles to the nearest degree ?

Answers

Answer:

  41°, 56°, 83°

Step-by-step explanation:

We can find the largest angle from the law of cosines:

  c² = a² +b² -2ab·cos(C)

  C = arccos((a² +b² -c²)/(2ab))

  C = arccos((4² +5² -6²)/(2(4)(5))) = arccos(5/40) ≈ 82.8192°

Then the second-largest angle can be found the same way:

  B = arccos((4² +6² -5²)/(2·4·6)) = arccos(27/48) ≈ 55.7711°

Of course the third angle is the difference between the sum of these and 180°:

  A = 180° -82.8192° -55.7711° = 41.4096°

Rounded to the nearest degree, ...

  the angles of the triangle are 41°, 56°, 83°.

What tool is used to draw circles

Answers

Answer:

Pair of compasses.

Step-by-step explanation:

These are used to inscribe circles/arcs.

Compasses are used in maths, navigation,e.t.c.

Hope it helps.


Using the diagram below, solve the right triangle. Round angle measures to the
nearest degree and segment lengths to the nearest tenth.

Answers

Answer:

m∠A = 17 degrees       m∠B = 73 degrees     m∠C = 90 (given)    a =   12 (given)    b =  40           c = 42 (given)

Step-by-step explanation:

Use sin to solve m∠A

sin x = 12/42     Simplify

sin x = 0.2857   Use the negative sin to solve for x

sin^-1 x =  17 degrees

Add together all of the angle measures to solve for m∠B

17 + 90 + x = 180    Add

107 + x = 180

-107        -107

x = 73 degrees

Use Pythagorean Theorem to solve for b

12^2 + x^2 = 42^2     Simplify

144 + x^2 = 1764

-144            -144

x^2 = 1620               Take the square root of both sides

x = 40

Prime factorization of 45
A. 2³×5
B. 3²×5
C. 5²×3
D. 5²×9

Answers

Answer:

Hello, your answer is:

B. 3²×5

Step-by-step explanation:

Prime factorization of 45 is:

45 = 9 x 5

= 3²×5

Hope this helps you.. Good Luck

Answer:

B. 3² × 5

Step-by-step explanation:

45 can be written as a product of its prime factors.

45 = 3 × 3 × 5

45 = 3² × 5

Help me with this please I will give you Brainliest

Answers

Answer

h = 8.12 cm

Explanation

Area of a parallelogram = b • h

We know the area is 20.3 cm^2 and that the base is 2.5cm.

Therefore 20.3 cm^2 = 2.5h

20.3/2.5 = 8.12 cm

h = 8.12 cm
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