Question

1. City wants to make a 98% confidence interval for the average height of students. The margin of error is to be more than 2.5 inches. From experience, you believe the standard deviation of the hights to be 3 inches. What is the minimum required number of students you must measure?

2. According to advertising claims. allowed couples to increase the chances of having a baby girl. Suppose we conduct an experiment with 100 couples who want to have baby girls and they all use this product. 40 of them had girls. Does this product help couples have more chance of having a baby girl? Do a hypothesis test. α = 0.05

A) State the null and alternative hypotheses

B) Calculate the test static. Show every work

C) What is your statistical conclusion based on the test statistic obtained part (b)?

D) Explain your results to people who don't know statistics.

Answer 1

1)

Solution :

Given that,

standard deviation = = 3

margin of error = E = 2.5

At 98% confidence level the z is ,

= 1 - 98% = 1 - 0.98 = 0.02

/ 2 = 0.02 / 2 = 0.01

Z_/2 = Z_0.01 = 2.33

Sample size = n = ((Z_/2 * ) / E)²

= ((2.33 * 3) / 2.5)²

= 7.81 = 8

Sample size = 8

The minimum required number of students you must measure = 8