Por favor ayudame con esto? No lo entiendo :'(

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?

At 6 1/2 cents per pound of string beans how much does 7 pounds cost

How to find the exponential function y=ca^x, with points (1,2) and (2,1)