CAN SOMEONE PLEASE HELP ME ON THIS ONE PLEASE !!

The mean finish time was 185.52 with a standard deviation of 0.327 minute. the winning car driven by chris finished in 185.13. the previous year race had a mean finish time of 110.3 with a standard deviation of 0.106. the winning car that year driven by karen finished in 110.13 minutes. find their respective z-scores. chris - z-score karen “- z-score

Math i have no idea how to do a and b

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?