A survey of 728 students at a local elementary school determined that half the students were boys and half were girls. Among the girls 49% are blondes, 3% are red-heads, 10% have black hair, and the remainder have chestnut-brown hair. Among the boys 40% are blondes, 2% are red-heads, 8% have black hair, and the remainder have chestnut-brown hair. What is the most commonly represented category of student in the school?