A summer camp has 150 children coming for the summer. Out of them, 60% have applied for the water sports programme and 80% have applied for rock climbing. How many campers have applied for both? Choose one.
A) 50  B) 60  C) 70  D) 80  E) 90
The total number of campers coming for the summer is n = 150.   The number of campers who have applied for the water sports activities is 60% of it, thus   n (A)=60/100×150=6×15=90   The number of campers who have applied for rock climbing is 80%, thus   n (B)=80/100×150=8×15=120.   In order to calculate the number of campers who have applied for both programs we can use the following equation:   n (AnB)=n (A)+n (B) -n =90+120-150=50=60.   So, 60 campers have applied for both water sports and rock climbing.   ANSWER: 60
<result>B</result>
A summer camp has 150 children coming for the summer. Out of them, 60% have applied for the water sports programme and 80% have applied for rock climbing. How many campers have applied for both?