The mean number of close friends for the population of people living in the US is 5.72. A researcher predicts that the mean number of close friends for introverts is significantly less than the mean of the population. The mean number of friends for a sample of 26 introverts is 5.18. The standard deviation of the sample to estimate the population is 1.30.

alpha = 0.01, one-tailed

a. State the null hypothesis and a one-tailed hypothesis based on the information above.

b. State the critical t value with proper formatting, perform the appropriate t test, and report the calculated t value. Round to 2 decimals for calculations. Show work in detail. Critical t value: _________ Calculated t value: __________

c. Provide an interpretation for the null hypothesis.

d. Was the researcher correct in predicting the mean number of close friends is significantly less than the population?

e. Calculate the effect size index, interpret and describe the effect size index. Show work in detail. d = _______________

Interpretation: ________________________

Description: _____________________________