Hi ,

I'm having problems understanding null hypothesis and t-statistics. Especially this question(below):

12. You will have complete sales information for last month in a week, but right now you have data from a random sample of 40 stores. The mean change in sales in the sample is +3.8% and the standard deviation of the changes is 12%. Are average sales for all stores different from last month?

a. State appropriate null and alternative hypotheses. Explain how you decide between the one-and two-sided alternatives.

H0: µ = .038

Ha: µ ≠ .038

I used the two-sided alternative because it wants to know if the average sales for all stores are different from last month.

b. Find the t statistics and its P-value. State your conclusion.

t = X¯ - .038/(.12/√40 )= 2.00

P-value = .052

Answer: t=2 and p=.052

Are these answers right?

Please help and Thank You

I'm having problems understanding null hypothesis and t-statistics. Especially this question(below):

12. You will have complete sales information for last month in a week, but right now you have data from a random sample of 40 stores. The mean change in sales in the sample is +3.8% and the standard deviation of the changes is 12%. Are average sales for all stores different from last month?

a. State appropriate null and alternative hypotheses. Explain how you decide between the one-and two-sided alternatives.

H0: µ = .038

Ha: µ ≠ .038

I used the two-sided alternative because it wants to know if the average sales for all stores are different from last month.

b. Find the t statistics and its P-value. State your conclusion.

t = X¯ - .038/(.12/√40 )= 2.00

P-value = .052

Answer: t=2 and p=.052

Are these answers right?

Please help and Thank You

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