In a school, 0.9 of the girls and 0.1 of the boys take part in quizzes. There is an equal number of boys and girls who do not take part in quizzes. If 216 pupils do not take part in quizzes, how many more pupils take part in quizzes than those who do not take part in quizzes?

Girls		Boys
Take part	Do not take part	Take part	Do not take part
9x9	1x9	1	9
	1x9		1x9
81 u	9 u	1 u	9 u

0.9 = ⁹₁₀
Girls that take part : Girls that do not take part = 9 : 1

0.1 = ¹₁₀
Boys that take part : Boys that do not take part = 1 : 9

The number of boys who do not take part is repeated.  Make the number of boys who do not take part the same.  LCM of 1 and 9 is 9.

Number of pupils who do not take part in quizzes
= 9 u + 9 u
= 18 u

18 u = 216

1 u = 216 ÷ 18 = 12

Number of pupils who take part in quizzes
= 81 u + 1 u
= 82 u

Number of more pupils who take part in quizzes than those who do not take part in quizzes
= 82 u - 18 u
= 64 u
= 64 x 12
= 768

Answer(s): 768