Question

A local weather enthusiast wants to see if the last five summers have been warmer than normal for Eloy, Arizona. From the National Oceanic and Atmospheric Administration (NOAA), he knows the 30-year average for July was 90° with a standard deviation of 2.1°. The last five summers recorded have an average of 93.5°. If he uses a = 5%, which of the following would be valid based on the data he has gathered?

Answer 1

Answer:

Step-by-step explanation:

This is a question on hypothesis testing.

Population mean based on 30 year average for July was 90 with

a std deviation of 2.1

Sample of 5 shows average 93.5

To check whether sample average = population average

H0: x bar =90

Ha: x bar not equal 90(Two tailed test)

Test statistic = $\frac{93.5-90}{\frac{2.1}{\sqrt{5} } }$

=3.73

Since this lies outside the range (-1.96, 1.96) we reject null hypothesis

Hence we cannot say sample mean equals 90

Answer 2

Answer:

D

Step-by-step explanation: