Calculating the standard error

Reference no: EM1318195

Q1) Random sample of 49 lunch customers was taken at restaurant. Average amount of time customers in sample stayed in restaurant was 33 minutes. From past experience, it is known that population standard deviation is 10 minutes.

a) Calculate the standard error.

b) With 95% confidence, find out the margin of error?

c) Create a 95% confidence interval for true average amount of time customers spent in the restaurant.

d) With 95% confidence, how large of sample would have to be taken to give a margin of error of 2.5 minutes or less?

Q2) Bank has kept records of checking balances of its customers and found out that average daily balance of its customers is $300 with standard deviation of $48. Random sample of 144 checking accounts is selected.

a) Determine the probability that the sample mean will be more than $306.60?

b) Determine the probability that the sample mean will be less than $308?

c) Determine the probability that sample mean will be between $302 and $308?

d) Determine the probability that the sample mean will be at least $296?

Reference no: EM1318195

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