Question

An IQ test scoring is designed to have mean of 100 and a standard deviation of 15. The scores are known to be normally distributed. A principal at a private school wants to investigate whether the average IQ of the students at her school is statistically different from the designed mean. She randomly samples from the school and has 15 students take the IQ test. The average test score of the sample is 95 and the sample standard deviation is 2. Use α = .10

1. Follow the 7 steps for hypothesis testing to solve this problem using the critical region method.

2. Calculate the p value.

3. Calculate the 90% confidence interval. Look to see if the hypothesized mean is in confidence intervals.

4. Do you come to the same conclusion using critical region, p value and confidence intervals?

find upper and lower intervals,state null and alternative hypothsis

Answer 1