The late 1960s and early 1970s were years of turmoil in the U.S. Psycholo-

gists thought that rioting was related (among other things) to temperature, with hotter weather making people more aggressive. ¹⁴ Two investigators, however, argued that "the frequency of riots should increase with temperature through the mid-80s but then go down sharply with increases in temperature beyond this level."

To support their theory, they collected data on 102 riots over the period 1967-

71, including the temperature in the city where the riot took place. They plotted a histogram for the distribution of riots by temperature (a sketch is shown below). There is a definite peak around 85°. True or false, and explain: the histogram shows that higher temperatures prevent riots. P-968