In a class of 88 students, the number of girls is 20% more than the number of boys. The average height of the boys is 164 cm, and the average height of the girls is 4 cm less than the average height of all the boys and girls in the class. What is the average height (in cm) of all the students in the class?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1 i.e. 159.2.
Let boys = b ⇒ girls = 1.2b
b + 1.2b = 88 ⇒ b = 40, girls = 48
Boys' avg = 164, girls' avg = x − 4, total avg = x
Total height:
40×164 + 48(x−4) = 88x
⇒ 6560 + 48x − 192 = 88x
⇒ 6368 = 40x ⇒ x = 159.2