Help as soon as possibly ( this is from my last question)

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?

Linda loans her friend $250 with a 5% monthly intrest rate. how much was the whole loan?

What is the value of x in the equation7x+2y=48 when y=3