Round 0.006772 to 1 significant figure

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?

How many revolutions will a car wheel of diameter 28 in. make over a period of half an hour if the car is traveling at 60 mi/hr? the final answer is supposedly 21,609 but i have no idea how to get that, show work : )

Rewrite the point-slope equation in slope-intercept form: y - 3 = 2(x + 4)