Solve for n.
19n+20≥1

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?

The parabola x= √y-9 opens: a.)up b.)down c.)right d.)left

Can someone me out here number 4 plz