Dr. N. M. Arr was called in to help analyze the 1H NMR spectrum of a mixture of compounds known to contain only C, H, and Br. The mixture showed two singlets-one at 1.8 ppm and the other at 2.7 ppm-with relative integrals 1 : 6, of respectively. Dr. Arr determined that the spectrum was that of a mixture of bromomethane and 2-bromo-2 methylpropane. What was the ratio of bromomethane to 2-bromo-2-methylpropane in the mixture?