What equation represents a line with a slope of zero

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 value of x is in the solution set of 4x – 12 s 16 + 8x?

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way