HELP ASAP!

a. 4/25
b. 1/3
c. 1/2
d. 1/5

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?

What is the value of the expression 9+n/3-6 when n = 12? 1. 5. 7. 12.

If 25% of y is 30, what is 60% of y?