Multiple choice

The average of three number is 84. If another number is included the average becomes 80. If another number is included which is 3 more than 4th number replace the 1st number then average of four number becomes 79. Find the value of 1st number?

  1. 12

  2. 11

  3. 9

  4. 75

  5. 3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The first three numbers total 3 x 84 = 252, and the first four total 4 x 80 = 320, so the fourth number is 68. Replacing the first number with 71 makes the total 316, so the first number was 320 + 71 - 316 = 75.

Keep practicing — related questions