Some help doing a final

Charles is on a 8 1/2 mile bike ride. he stops for a rest after he’s gone 5 2/5 miles. how much farther does he still have to go?

Suppose a least-squares regression line is given by modifyingabove y with caret equals 4.302 x minus 3.293. what is the mean value of the response variable if xequals20?

The number of revolutions of two pulleys is inversely proportional to their diameters. if a 24-inch diameter pulley making 400 revolutions per minute is belted to an 8-inch diameter pulley, find the number of revolutions per minute of the smaller pulley.