We use a t distribution for inference about a population mean instead of the standard Normal distribution:

a. if the original population does not have a Normal distribution.
b. if we do not have a simple random sample.
c. if we do not know the population standard deviation and must use the sample standard deviation.
d. if we do not know the population mean and must use the sample mean.

Jason started last week with $900 in his checking account. during the week, he wrote the checks below. at the end of the week, jason received a paycheck for $534.59. he recorded all of these transactions in his check register. trans typ./ check no. date description of transaction payment/ debit deposit/ credit (+) balance 900 00 241 12/4 miller's food market 53.21 53 21 groceries 846 79 242 12/7 frank's auto parts 24.05 24 05 oil and filter 822 74 243 12/8 mike's barber shop 15.00 15 00 haircut 807 74 deposit 12/9 paycheck 534.59 534 59 1,342 33 evaluate jason's check register. a. jason did a good job; everything is correct. b. the final balance is wrong; jason did not add everything correctly. c. jason should have written debit instead of deposit for the transaction type. d. jason entered the amount for his paycheck in the wrong column.