1/2 of the pupils in a class are girls. 3/8 of the girls and 1/4 of the boys wear spectacles. what fraction of the pupils wear spectacles?
3/8 + 1/4 = 3/8 + 2/8= 5/8
X pupils in class.
X/2 girls in class.
X/2 boys in class.
3/8 * X/2 = 3x/16 Girls wear glasses.
1/4 * X/2 = x/8 Boys wear glasses.
3x/16 + x/8 = 3x/16 + 2x/16 = 5x/16 Pupils wear glasses.
(5x/16)/X = 5/16 of the pupils wear glasses.
.