The "MANEJO" school is an institution in which there are 210 students learning to drive, one of the activities is a school trip to a lake, based on study data above, the average time of each trip is...

The "MANEJO" school is an institution in which there are 210 students learning to drive,
one of the activities is a school trip to a lake, based on study data
above, the average time of each trip is 165 minutes, and the variance is 144 minutes,
the institution analyzes the performance of each student, this time because there are many, all
students were divided into 6 groups, each group with the same number of students, and were
identified with the letters A, B, C, D, E and F, each group was taken as a sample, and to make
an analysis, group D was taken, you are asked to help calculate:
a) The probability that the average time of the sample does not exceed 168 minutes.
b) The probability that the sample mean time is greater than the equivalent time
to the population mean plus 8 percent of an hour.