Test Statistic

TWO tailed 

A grocery store is analyzing their sales. A sample of 40 receipts has an average value of $137 and standard deviation of $30.20 Use this information to test whether or not the mean in sales value at this store is different from $150? Use α= 0.1

a. State null & alternate hypotheses

b. Calculate Z test statistic

c. Determine Z critical

d. State conclusion CLEARLY with the evidence.

2. A hospital group operates 33 clinics in Indiana and Illinois. A study was conducted to estimate the difference in mean time spent per visit for men and women. Previous studies indicated that the standard deviation is 11 min, for men and 16 min. for women. A random sample of 100 men and 100 women at the two states was observed. The resulting sample means were 34.5 min. for men and 42.4 min. for women. Is the difference between men and women significant at α = 0.05

a. State null & alternate hypotheses

b. What is the ‘degree of freedom’?

c. Calculate t test statistic

d. Determine t critical

e. Is the difference in mean time between men and women significant?