On typical summer days, field crickets nibble, jump, and chirp now and then. But at a night when great numbers congregate, chirping seems to become a serious business and tends to be in unison. In 1897, A. E. Dolbear (Am. Naturalist, 31,970) reported that this social chirping rate was dependent on the temperature as given by (number of chirps in 15 s) + 40 = (temperature, OF)

Assuming that the chirping rate is a direct measure of the metabolic rate, find the activation energy in kJ/mol of these crickets in the temperature range 60430°F.