The scores from a state standardized test have a mean of 80 and a standard deviation of 10. The distribution of the scores is roughly bell shaped. to find the percentage of scores that lie between 60 and 80.

Answer:

With 99% confidence the proportion of all smart phones that break before the warranty expires is between 0.041 and 0.069.

Step-by-step explanation:

We have to calculate a 99% confidence interval for the proportion.

The sample proportion is p=0.055.

[tex]p=X/n=97/1750=0.055[/tex]

The standard error of the proportion is:

[tex]\sigma_p=\sqrt{\dfrac{p(1-p)}{n}}=\sqrt{\dfrac{0.055*0.945}{1750}}\\\\\\ \sigma_p=\sqrt{0.00003}=0.005[/tex]

The critical z-value for a 99% confidence interval is z=2.576.

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

[tex]MOE=z\cdot \sigma_p=2.576 \cdot 0.005=0.014[/tex]

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

[tex]LL=p-z \cdot \sigma_p = 0.055-0.014=0.041\\\\UL=p+z \cdot \sigma_p = 0.055+0.014=0.069[/tex]

The 99% confidence interval for the population proportion is (0.041, 0.069).

Answer:

nx^(n-1)

Step-by-step explanation:

Answer:

It cannot be extended.

Step-by-step explanation:

Consider the function [tex]f(x,y) = \frac{x^2-y^2}{x^2+y^2}[/tex]. To extend this functions so it is continous at (0,0) we must define [tex] f(0,0) = \lim_{(x,y)\to(0,0)\frac{x^2-y^2}{x^2+y^2}[/tex]. However, this implies that the limit exists. So, we should find if the limit exists or not.

In this case, consider the case in which y =0. When y=0 then

[tex]\lim_{(x,y)\to(0,0) \frac{x^2-0^2}{x^2+0^2} = \lim_{x\to 0}\frac{x^2}{x^2}= 1[/tex]

But, when x=0, we get

[tex]\lim_{(x,y)\to(0,0) \frac{0^2-y^2}{0^2+y^2} = \lim_{y\to 0}\frac{-y^2}{y^2}=-1[/tex].

So, since the limit depends on how we approach to the point (0,0) the limit does not exist. So we can't extend f(x,y) so it is continous.

Answer:

{$3.60; $3.68}

Step-by-step explanation:

The confidence interval for a sample of size 'n', with mean price 'X' and standard deviation 's' is determined by:

[tex]X\pm z*\frac{s}{\sqrt n}[/tex]

The z-score for a 95% confidence interval is 1.96.

Applying the given data, the lower and upper bounds of the confidence interval are:

[tex]3.64\pm 1.96*\frac{0.0835}{\sqrt 20} \\L=\$3.60\\U=\$3.68[/tex]

The confidence interval for the mean price received by farmers for corn sold in January is:

CI : {$3.60; $3.68}

Answer:

2.598 and -2.598.

Step-by-step explanation:

f(x) = 2 cos x + sin 2x

f'(x) = -2 sin x + 2 cos 2x = 0   for turning points.

cos 2x =  1 - 2 sin^2 x so we have

-2 sin x + 2 - 4 sin^2 x = 0

4sin^2 x + 2 sin x - 2 = 0

2(2 sin^2 x + sin x - 1) = 0

2(2sinx - 1)(sinx + 1) = 0

sin x  = 0.5, -1   when  f(x) is at a turning point.

x = π/6,  -π/2, 5pi/6

The second derivative is  2 cos x + 2 * -2 sin 2x

= 2 cos x - 4 sin 2x

When x = π/6, this is negative , when x = -π/2 it is positive

so x = π/6 gives a maximum f(x) and x = -π/2 gives 0 so this is a point of inflection

When x = π/6 , f(x) = 2.598

When x = 5pi/6,  f(x) = -2.598.

Answer:

x = 74.3

Step-by-step explanation:

Using the trigonometric ratio formula, the missing side, x, of the right angled triangle, can be found as follows:

Ѳ = 22°,

adjacent side length = x

Opposite side length = 30

Thus, we would apply the formula:

tan Ѳ = opposite length/adjacent length

[tex] tan 22 = \frac{30}{x} [/tex]

Multiply both sides by x

[tex] tan 22*x = \frac{30}{x}*x [/tex]

[tex] tan 22*x = 30 [/tex]

[tex] 0.4040*x = 30 [/tex]

Divide both sides by 0.4040 to make x the subject of the formula

[tex] \frac{0.4040*x}{0.4040} = \frac{30}{0.4040} [/tex]

[tex] x = \frac{30}{0.4040} [/tex]

[tex] x = 74.26 [/tex]

x ≈ 74.3 (to the nearest tenth)

Answer:

y = -2x +4

Step-by-step explanation:

The slope intercept form of a line is

y = mx+b  where m is the slope and b is the y intercept

y = -2x +4

Answer:

3/4

Step-by-step explanation:

Use [tex]\frac{rise}{run}[/tex]. From the bottom red point, you have to go up 3 and left 4 to get to the top point. That's your answer.

Answer:

0.6

Step-by-step explanation:

3+2=5

P (white) = 3/5 = 0.6

(Hopefully this works, if not, on hearty maths you can go back to your assigned tasks page and go back onto the task to get a new question if that makes sense)

Answer:

-2/5

Step-by-step explanation:

The slope of two parallel lines will be the same.

Here, our equation is 5y + 2x = 12. Let's find the slope by isolating y:

5y + 2x = 12

5y = -2x + 12

y = (-2/5)x + 12/5

So, the slope is -2/5.

Thus, the slope of the line parallel to the given one will be -2/5.

~ an aesthetics lover

Answer:

-2/5

Step-by-step explanation:

5y+2x=12

Solve for y

Subtract 2x

5y = -2x+12

Divide by 5

5y/5 = -2/5 x +12/5

y = -2/5x +12/5

The slope is -2/5

Parallel lines have the same slope

Answer:

  x = 17.349

Step-by-step explanation:

The right-most x-intercept is 17.349, where the curve continues upward to the right.

Answer:

The probability that the mean of my sample will be between 24 and 25 cm

P(24 ≤X⁻≤25) = 0.4772

Step-by-step explanation:

Step(i):-

Given mean of the Population  'μ'= 25c.m

Given standard deviation of the Population 'σ' = 8c.m

Given sample size 'n' = 256

Let X₁ = 24

[tex]Z_{1} = \frac{x_{1}-mean }{\frac{S.D}{\sqrt{n} } } = \frac{24-25}{\frac{8}{\sqrt{256} } } = -2[/tex]

Let X₂ = 25

[tex]Z_{2} = \frac{x_{2}-mean }{\frac{S.D}{\sqrt{n} } } = \frac{25-25}{\frac{8}{\sqrt{256} } } = 0[/tex]

Step(ii):-

The probability that the mean of my sample will be between 24 and 25 cm

P(24 ≤X⁻≤25) = P(-2≤ Z ≤0)

                     = P( Z≤0) - P(Z≤-2)

                     = 0.5 + A(0) - (0.5- A(-2))

                     = A(0) + A(2)        ( ∵A(-2) =A(2)

                     = 0.000+ 0.4772

                     = 0.4772

Final answer:-

The probability that the mean of my sample will be between 24 and 25 cm

P(24 ≤X⁻≤25) = 0.4772

Answer:

[tex]slope = \dfrac{-680}{9}[/tex]

Step-by-step explanation:

We are given coordinates of two points:

Let the points be A and  B respectively:

[tex]A(\dfrac{7}{20}, \dfrac{8}{3})\\B(\dfrac{3}{8}, \dfrac{7}{9})[/tex]

To find the slope of line AB.

Formula for slope of a line passing through two points with coordinates [tex](x_1, y_1)[/tex] and [tex](x_2,y_2)[/tex] is given as:

[tex]m = \dfrac{y_2- y_1}{x_2- x_1}[/tex]

Here, we have:

[tex]x_2 = \dfrac{3}{8}\\x_1 = \dfrac{7}{20}\\y_2 = \dfrac{7}{9}\\y_1 = \dfrac{8}{3}\\[/tex]

Putting the values in formula:

[tex]m = \dfrac{\dfrac{7}{9}- \dfrac{8}{3}}{\dfrac{3}{8}- \dfrac{7}{20}}\\\Rightarrow m = \dfrac{\dfrac{7-24}{9}}{\dfrac{15-14}{40}}\\\Rightarrow m = \dfrac{\dfrac{-17}{9}}{\dfrac{1}{40}}\\\Rightarrow m = \dfrac{-17\times 40}{9}\\\Rightarrow m = \dfrac{-680}{9}[/tex]

So, the slope of line AB passing through the given coordinates is:

[tex]m = \dfrac{-680}{9}[/tex]

Answer:

(B)[tex]\dfrac{dA}{dt}=8-0.004A[/tex]

Step-by-step explanation:

Volume of fluid in the tank =1000 gallons

Initial Amount of Salt in the tank, A(0)= 30 pounds

Incoming brine solution of concentration 2 pounds of salt per gallon is pumped in at a rate of 4 gallons per minute.

Rate In=(concentration of salt in inflow)(input rate of brine)

[tex]=(2\frac{lbs}{gal})( 4\frac{gal}{min})=8\frac{lbs}{min}[/tex]

The resulting mixture is pumped out at the same rate, therefore:

Rate Out =(concentration of salt in outflow)(output rate of brine)

[tex]=(\frac{A(t)}{1000})( 4\frac{gal}{min})=\frac{A}{250}[/tex]

Therefore:

The rate of change of amount of salt in the tank,

[tex]\dfrac{dA}{dt}=$Rate In-Rate out\\\dfrac{dA}{dt}=8-\dfrac{A}{250}\\\dfrac{dA}{dt}=8-0.004A[/tex]

Answer:

7/ (3a-1)

Step-by-step explanation:

3a^2 -13a +4        28+7a

------------------ * --------------------

9a^2 -6a+1         a^2 -16

Factor

(3a-1)(a-4)           7(4+a)

------------------ * --------------------

(3a-1) (3a-1)        (a-4)(a+4)

Cancel like terms

1                    7

------------------ * --------------------

(3a-1)                  1

Leaving

7/ (3a-1)

Answer:

a. P-value = 0.1589

b. P-value = 0.0016

Step-by-step explanation:

a. This is a hypothesis test for the difference between populations means.

The claim is that the two types of steel have different true average fracture toughness values.

Then, the null and alternative hypothesis are:

[tex]H_0: \mu_1-\mu_2=0\\\\H_a:\mu_1-\mu_2\neq 0[/tex]

The significance level is α=0.05.

The sample 1, of size n1=100 has a mean of 60.7 and a standard deviation of 1.  The sample 2, of size n2=100 has a mean of 60.5 and a standard deviation of 1.

The difference between sample means is Md=0.2.

[tex]M_d=M_1-M_2=60.7-60.5=0.2[/tex]

The estimated standard error of the difference between means is computed using the formula:

[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2+\sigma_2^2}{n}}=\sqrt{\dfrac{1^2+1^2}{100}}\\\\\\s_{M_d}=\sqrt{\dfrac{2}{100}}=\sqrt{0.02}=0.1414[/tex]

Then, we can calculate the t-statistic as:

[tex]t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{0.2-0}{0.1414}=\dfrac{0.2}{0.1414}=1.4142[/tex]

The degrees of freedom for this test are:

[tex]df=n_1+n_2-2=100+100-2=198[/tex]

This test is a two-tailed test, with 198 degrees of freedom and t=1.4142, so the P-value for this test is calculated as (using a t-table):

[tex]P-value=2\cdot P(t>1.4142)=0.1589[/tex]

As the P-value (0.1589) is greater than the significance level (0.05), the effect is not significant.

The null hypothesis failed to be rejected.

There is not enough evidence to support the claim that the two types of steel have different true average fracture toughness values.

b. As the sample size changes, the standard error and the degress of freedom change.

The estimated standard error of the difference between means is computed using the formula:

[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2+\sigma_2^2}{n}}=\sqrt{\dfrac{1^2+1^2}{500}}\\\\\\s_{M_d}=\sqrt{\dfrac{2}{500}}=\sqrt{0.004}=0.0632[/tex]

Then, we can calculate the t-statistic as:

[tex]t=\dfrac{M_d-(\mu_1-\mu_2)}{s_{M_d}}=\dfrac{0.2-0}{0.0632}=\dfrac{0.2}{0.0632}=3.1623[/tex]

The degrees of freedom for this test are:

[tex]df=n_1+n_2-2=500+500-2=998[/tex]

This test is a two-tailed test, with 998 degrees of freedom and t=3.1623, so the P-value for this test is calculated as (using a t-table):

[tex]P-value=2\cdot P(t>3.1623)=0.0016[/tex]

As the P-value (0.0016) is smaller than the significance level (0.05), the effect is significant.

The null hypothesis is rejected.

There is enough evidence to support the claim that the two types of steel have different true average fracture toughness values.

i think it is ur required ans..

Answer:

the slope equation is y2 - y1 divided by x2 - x1

Step-by-step explanation:

so the answer would be 3 over 2 because of this method

Answer:

3/2

Step-by-step explanation:

Use the easy rise over run method.

start at the point (50,20) then go up 3 units and 2 units to the right to get the next point.

3/2 should be the slope.

Hope I helped you!

Answer:

8, 8, 13

Step-by-step explanation:

The three numbers 8, 8, 13 have a range of 5.

13 - 8 = 5

The mode is 8, the repeated number.

Answer:

need pls

Step-by-step explanation:

Answer:

Step-by-step explanation:

The angle next to 90 degrees is also 90 degrees and it's supplementary

the angle next to 133 degrees is 47 degrees and it's also supplementary

p + 90 + 47 = 180

p + 137 = 180

p = 43 degrees

the solution is d

Answer:

The point estimate for the mean mpg of hybrid cars is 30 mpg.

Step-by-step explanation:

A confidence interval has two bounds, a lower bound and an upper bound.

A confidence interval is symmetric, which means that the point estimate used is the mid point between these two bounds, that is, the mean of the two bounds.

In this problem, we have that:

Lower bound: 22

Upper bound: 38

Point Estimate:

(22 + 38)/2 = 30

The point estimate for the mean mpg of hybrid cars is 30 mpg.

Answer: 2 1/2 or 2.5 hours

Step-by-step explanation:

Add 360 and 330

360 + 330 = 690

Divide 1,725 by 690

1,725 / 690 = 2.5

The two planes will meet in 2.5 hours

The speed is the distance covered by an object at a particular time. The time it will take for the two planes to meet is 2.5 hours.

The speed is the distance covered by an object at a particular time. Therefore, it is the ratio of distance and time.

[tex]\rm{Speed = \dfrac{Distance}{Time}[/tex]

Given that the speed of the two planes is 360 km/hr and 330 km/hr. Therefore, the relative speed of the two planes with respect to each other is,

Relative speed = 360 km/hr + 330 km/hr

                         = 690 km/hr

Now, since the total distance between the two cities is 1725 km. Therefore, the time it will take for two planes to meet is,

Time = Distance /Speed

         = 1725 km / 690 km/hr

         = 2.5 hour

Hence, the time it will take for the two planes to meet is 2.5 hours.

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Answer: A

Step-by-step explanation:

Answer: A.

Step-by-step explanation:

A composition of reflections over two parallel lines is equivalent to a translation.

Answer:

The correct answer would be C

Step-by-step explanation:

please mark brainliest

The choice which best compares the volume of the cylinders is; Choice B; The volume of cylinder B is the same as that of cylinder A.

From geometry, It can be concluded that the volume of a solid shape is the product of its cross sectional area and the height over which the area spans. On this note, since the volume of a cylinder is dependent on the radius and height of the cylinder, both cylinders have equal volumes.

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Answer:

The radioactive decay constant or  k = ln (.5) / Half-Life

Half-Life =  -.693147 / .00012

Half-Life = -5,776.225  years

We'll call beginning amount as 100%

Ending Amount = Beginning Amount / 2^n (where n = # of half-lives)

n = 4,050 / 5,776.225 = 0.7011499725

Ending Amount = 100% / 2^0.7011499725

Ending Amount = 100% / 1.625800202

Ending Amount = 61.5081729452%

Ending Amount = 61.5 % (rounded)

Step-by-step explanation:

Answer:

(D)Jaleel's method is correct because 2(x-2)=2x-4.

Step-by-step explanation:

Jaleel and Lisa are simplifying the expression 2(x-2)+2 as shown.

[tex]J$aleel's Method: \left\{\begin{array}{ccc}2 (x -2) + 2 \\= 2 x - 4 + 2 \\= 2 x - 2\end{array}\right[/tex]

[tex]L$isa's Method: \left\{\begin{array}{ccc}2 (x-2) + 2 \\= 2 x -2 + 2 \\= 2 x\end{array}\right[/tex]

We can see that Jaleel's method is correct because:

2(x-2)=2x-4.

When you expand, you must multiply the term outside by all the terms inside the bracket.

The correct option is D.

Answer:

Jaleel is correct because 2 (x minus 2) equals 2 x minus 4.

D is correct

Step-by-step explanation:

i just took the quiz.

Answer:

m = 0.5

Step-by-step explanation:

m = (y2 - y1) / (x2 - x1)

= (0.25 - 0) / (0.5 - 0)

= 0.25/0.5

= 0.5

Answer:

  (x, y) = (-3, -2)

Step-by-step explanation:

Perhaps this is a system of equations you want the solution for.

Since you have an expression for y, substitution is a viable approach.

  5x +7(x+1) = -29 . . . . . . substitute for y

  12x = -36 . . . . . . subtract 7 and simplify

  x = -3 . . . . . . . . . divide by 12

  y = (-3) +1 = -2 . . . use the expression for y

The solution is (x, y) = (-3, -2).

Answer:

12,780

Step-by-step explanation:

Initial population = 9000

grows 7% of 9000= 630 people in a year

after 6 yrs, number of added people = 630× 6=3780 ...... totally, population = 9000+ 3780

= 12,780

The population of the town after 6 years will be 13506.

Thus, the population of the town after 6 years will be 13506.

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