A ball is thrown from an initial height of 7 feet with an initial upward velocity of 21 ft/s. The ball's height h (in feet) after t seconds is given by the following. h=7+21t-16t²
Find all values of t for which the ball's height is 13 feet.
Round your answer(s) to the nearest hundredth.

What is the missing constant term in the perfect square that starts with x^2 -20x

One integer is 8 times another. if the product is 72, then find the integers

Lems1. the following data set represents the scores on intelligence quotient(iq) examinations of 40 sixth-grade students at a particular school: 114, 122, 103, 118, 99, 105, 134, 125, 117, 106, 109, 104, 111, 127,133, 111, 117, 103, 120, 98, 100, 130, 141, 119, 128, 106, 109, 115,113, 121, 100, 130, 125, 117, 119, 113, 104, 108, 110, 102(a) present this data set in a frequency histogram.(b) which class interval contains the greatest number of data values? (c) is there a roughly equal number of data in each class interval? (d) does the histogram appear to be approximately symmetric? if so, about which interval is it approximately symmetric?