They or both correct

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

nexus9112 [7]

Answer:

a) $\sigma = 0.167$

b) We need a sample of at least 282 young men.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by

$Z = \frac{X - \mu}{\sigma}$

This Zscore is how many standard deviations the value of the measure X is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

(a) What standard deviation must x have so that 99.7% of allsamples give an x within one-half inch of μ?

To solve this problem, we use the 68-95-99.7 rule. This rule states that:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviations of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we want 99.7% of all samples give X within one-half inch of $\mu$ . So $X - \mu = 0.5$ must have $Z = 3$ and $X - \mu = -0.5$ must have $Z = -3$ .

So

$Z = \frac{X - \mu}{\sigma}$

$3 = \frac{0.5}{\sigma}$

$3\sigma = 0.5$

$\sigma = \frac{0.5}{3}$

$\sigma = 0.167$

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

You know from government data that heights of young men are approximately Normal with standard deviation about 2.8 inches. This means that $\sigma = 2.8$

The standard deviation of a sample of n young man is given by the following formula

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

We want to have $s = 0.167$

$0.167 = \frac{2.8}{\sqrt{n}}$

$0.167\sqrt{n} = 2.8$

$\sqrt{n} = \frac{2.8}{0.167}$

$\sqrt{n} = 16.77$

$\sqrt{n}^{2} = 16.77^{2}$

$n = 281.23$

We need a sample of at least 282 young men.

6 0

2 years ago

Please help!!!!!!!!!!!!!!!! Will mark brainliest! thanks!

madreJ [45]

$gpm = 29.7 \times {d}^{2} \times \sqrt{np}$
this formula is used to determine gpm (gallons per minute) of flow with a known hose diameter (d) and nozzle pressure (np). The constant (29.7) is consistent when figuring flow with in gallons with a know pressure expressed in psi (pounds per square inch).

Scenario example: a firefighter is using a handline to fight fire with an 1 3/4 inch line with a nozzle pressure of 100 psi. How much water is the firefighter flowing when fighting fire?

$gpm = 29.7 \times {1.75}^{2} \times \sqrt{100}$

3 0

2 years ago

Tatiana says the domain of this relationship is all x-

boyakko [2]

Answer:

no

Step-by-step explanation:

6 0

2 years ago

If 4 Americans, 3 Frenchman, and 3 Englishmen are to be seated in a row, how many seating arrangements are possible when people

Maurinko [17]

4 Americans can arrange themselves in 4! ways.similarly ,3 Frenchmen can arrange themselves in 3! ways.3 Englishmen can arrange themselves in 3! ways.now these 3 groups of same nationality people can be arranged among themselves in 3! ways.so total number of ways = 3!4!3!3!

6 0

2 years ago

4 team mates share 5 pizza show how much each person gets

Murrr4er [49]

Answer:

1 1/2

Step-by-step explanation:

Each person would equally get 1 pizza and the 1/2 of the last pizza

8 0

2 years ago