Is (4,1) (8,1) (8,2) (12,2) (12,3) (16,4) (20,3) a function, yes or no?!

Which of the following would represent the sum of 3 consecutive integers if x is the first integer?

Find the given elements if matrix d:

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?