Multiple choice! will mark brainliest if answer is correct and clear

Name the most appropriate metric unit for each measurement like the mass of cow

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 = y² - 9 opens: a.)up b.)down c.) right d.)left