More 10th-grade boys in four Northern California schools smoke marijuana than smoke tobacco, a Stanford University survey of more than 1,300 teen-agers found. According to the report, 14.4% of the boys smoke marijuana at least monthly and another 8.6% smoke it daily. Only 13.6% smoke tobacco cigarettes at least once a month, while 8.5% smoke them daily. Girls in the same age group prefer tobacco cigarettes, with 15.2% smoking them at least monthly and another 15.2% daily. Although 15.9% of the girls smoke marijuana on a monthly basis, only 3.7% smoke it daily.