Multiple choice

The weight of a body as calculated by the average of 7 different experiments is 53 kg. The average of the first three experiments is 54 kg. and the fourth is 3 kg greater than the fifth, while the average of the sixth and seventh experiment was 1 kg. less than the average of the first three. Find the weight of the body obtained by the fourth experiment.

  1. 51 kg.

  2. 52 kg.

  3. 57 kg.

  4. 53 kg.

  5. 54 kg.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total weight = 53×7 = 371 kg. First three experiments = 54×3 = 162 kg. Average of 6th and 7th = 54-1 = 53 kg, so their sum = 53×2 = 106 kg. Let 4th = x, then 5th = x-3. So 162 + x + (x-3) + 106 = 371. Therefore 2x + 265 = 371, giving 2x = 106 and x = 53 kg.

Keep practicing — related questions