Can someone plz explain to me how to do this !? Geometry

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

The table shows the balance of a money market account over time. write a function that represents the balance y (in dollars) after t years.

For the following geometric sequence, find the recursive formula. {-80, 20, -5, } i need : ')