Multiple choice

A weight of a body as calculated by the average of 7 different experiments is 53.735 gm. The average of the first three experiments is 54.005 gm, of the fourth is 0.004 gm greater than the fifth, while the average of the sixth and seventh experiments was 0.010 gm less than the average of the first three. find the weight of the body obtained by the fourth experiments.

  1. $49.353 gm$
  2. $51.712 gm$
  3. $53.072 gm$
  4. $54.512 gm$
  5. $56.123 gm$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total weight = 53.735 × 7 = 376.145. First 3 avg = 54.005, sum = 162.015. Sixth + seventh avg = 54.005 - 0.010 = 53.995, sum = 107.990. Fourth + fifth = 376.145 - 162.015 - 107.990 = 106.14. Let fifth = x, fourth = x + 0.004. 2x + 0.004 = 106.14, x = 53.068. Fourth = 53.072.

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