First try was incorrect

zalisa [80]

The correct
answer is 156

8 0

3 years ago

To estimate the mean height μ of male students on your campus, you will measure an SRS of students. You know from government dat

denis-greek [22]

Answer:

a) The standard deviation of x must be 0.25 inches.

b) We need a sample of 125 to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a).

Step-by-step explanation:

The 68-95-99.7 states that:

68% percent of the measures of a normally distributed sample are within 1 standard deviation of the mean.

95% percent of the measures of a normally distributed sample are within 2 standard deviations of the mean.

99.7% percent of the measures of a normally distributed sample are within 3 standard deviations of the mean.

The standard deviation of the population is 2.8. This means that $\sigma = 2.8$ .

(a) What standard deviation must x⎯⎯⎯ have so that 95% of all samples give an x⎯⎯⎯ within one-half inch of μ?

We want to have a sample in which 2 standard deviations are within 0.5 inches of the mean.

So, the standard deviation of the sample must be:

$2s = 0.5$

$s = 0.25$

The standard deviation of x must be 0.25 inches.

(b) How large an SRS do you need to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a)?

We have that the standard deviation of a sample of length n is given by the following formula:

$s = \frac{\sigma}{\sqrt{n}}$ .

We want $s = 0.25$ and we have $\sigma = 2.8$ . So

$0.25 = \frac{2.8}{\sqrt{n}}$

$0.25\sqrt{n} = 2.8$

$\sqrt{n} = 11.2$

$\sqrt{n}^{2} = (11.2)^{2}$

$n = 125.44$

We need a sample of 125 to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a).

8 0

4 years ago

Holly missed 7 of 181 school days this year. Approximately what percent of school days was Holly in attendance?

kogti [31]

Answer:

96.13%

Step-by-step explanation:

181-7=174. 174/181

5 0

3 years ago

You are designing a new container for powdered laundry detergent. You are considering a cylindrical container with a diameter of

Sidana [21]

Basically, you are asked to find the volume of a cylinder with a diameter of 14 inches and a height of 18 inches. The formula for the volume of a cylinder is

V = pi*(r^2)*h

r is just the half of the diameter. In this case, r = 14/2 = 7. Then,

V = pi*(7^2)*18
V = 2771 cubic inches

5 0

4 years ago

Find the Volume of this Octagonal Pyramid. "B" represents the Area of the octagon base.

Dominik [7]

Answer:

7.06 x 10^(-7) ft 3

Step-by-step explanation:

We have the formula to calculate the volume of an octagonal Pyraamid as following:

+) Volume of octagonal pyramid = 1/3 * Area of the base * Height

As given, the base of the pyramid is an octagon with area equal to 15mm2

=> Area of the base = 15 mm2

The height of the pyramid is the length of the line segment which is perpendicular to the base - which is the red line.

=> Height = 4mm

So we have:

Volume of octagonal pyramid = 1/3 * Area of the base * Height

= 1/3 * 15 * 4 = 20 mm3

As: 1 mm3 = 3.53 x 10^(-8) ft 3

=> 20 mm3 = 7.06x10^(-7) ft 3

So the volume of the pyramid is : 7.06 x 10^(-7) ft 3

6 0

4 years ago