here's an easy question of averages, but let's try to see innovative ways of solving this.
A class has 12 boys and x girls. Average score of boys and girls is 84 and 92 respectively. the average of the whole class is 86, what is the value of x?	Choose the correct choice from the following:
A) 6  B) 4  C) 8  D) 10  E) 12

Rationale: 12 ( 84 ) + 92 x / 12 + x = 86 1008 + 92 x / 12 + x = 86 1008 + 92 x = 86 ( 12 + x ) 1008 + 92 x = 1032 + 86 x x ' s one side , numbers one side we get , 92 x - 86 x = 1032 - 1008 6 x = 24 hence , x = 4 answer b
Answer: B