Okay I can't seem to figure out this problem. Would really appreciate any help that can be given.

A sample of 81 account balances of a credt company showed an average balance of $1,200 with a standard deviation of $126. You want to determine if the mean of all account balances si significantly different from $1150. Use a .05 level of confidence.

A) State the null hypothesis

B) WHat is the rejection rule?

C) COmpute the value of the test statitstic z.

D) What is your conclusion?

This is what I have come up with so far. Not sure if its right, but I gave it a try.

A) Ho: µ = 1150

Ha: µ ≠ 1150

B) Ho is rejected when z > 1.64

C) Sample size: 81

Mean: 1200

Std Dev: 126

Hypothesized value: 1150

Standard error: 14

Test statistic z: 3.571428571

D) Since z >1.64 Ho will be rejected.

A sample of 81 account balances of a credt company showed an average balance of $1,200 with a standard deviation of $126. You want to determine if the mean of all account balances si significantly different from $1150. Use a .05 level of confidence.

A) State the null hypothesis

B) WHat is the rejection rule?

C) COmpute the value of the test statitstic z.

D) What is your conclusion?

This is what I have come up with so far. Not sure if its right, but I gave it a try.

A) Ho: µ = 1150

Ha: µ ≠ 1150

B) Ho is rejected when z > 1.64

C) Sample size: 81

Mean: 1200

Std Dev: 126

Hypothesized value: 1150

Standard error: 14

Test statistic z: 3.571428571

D) Since z >1.64 Ho will be rejected.

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