Multiple choice

Average height of a group of 12 persons is 5 feet 3 inch. If 3 persons from the group are replaced by a person whose height is 6 feet, the average height becomes 5 feet 3.6 inch. Find the average height of 3 persons who left.

  1. 5 feet 3 inch

  2. 5 feet 4 inch

  3. 5 feet 2 inch

  4. 5 feet 4.5 inch
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original total = 12 × 63 = 756 inches. After replacement: 3 people left (average x) and 1 person joined (height 72 inches). New total = 12 × 63.6 = 763.2 inches. Change: -3x + 72 = 763.2 - 756 = 7.2, giving 3x = 64.8, so x = 64.8 inches = 5 feet 4 inches.

Keep practicing — related questions