Question

At net's hair salon, 35% of the customers dye their hair blond, 30% dye their eyebrows blond and 46% straighten their hair. 20% of the customers have none of these three procedures, while 11% take all of these three procedures. what percent of the customers come for exactly 2 of these 3 procedures?

Answer 1

Let a total of 100 people visit the salon.
Total = 100

Dye hair blonde (A) = 35 = 35
Dye Eyebrows blonde (B) = 30 = 30
Straighten Hair (C) = 46 = 46
Neither = 20% = 20
All Three = 11% =11

Total = A+B+C - (Sum of Exactly Two group overlaps) - 2*(All three) + Neither

100 = 35+30+46- (Sum of Exactly Two group overlaps) - 2*11 + 20

(Sum of Exactly Two group overlaps) = 35+30+46 – (100) - (2*11) + 20

(Sum of Exactly Two group overlaps) = 9 

%of customers coming for exactly 2 of the 3 procedures = 9%