Algebra-1

Original total number of trucks = 5 + 8 + 12 + 6 = 31.

First, calculate the original mean.

The sum of the products of the midpoints of each speed range and their frequencies is: [(35 * 5) + (45 * 8) + (55 * 12) + (65 * 6)] = (175 + 360 + 660 + 390) = 1585.

The orig...