Multiple choice

The average weight of $8$ person's increases by $2.5\ kg$ when a new person comes in place of one of them weighing $65\ kg$. What might be the weight of the new person?

  1. $76\ kg$
  2. $76.5\ kg$
  3. $85\ kg$

  4. Data inadequate

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the sum of weights of 8 persons be S. The new average is (S - 65 + x)/8 = (S/8) + 2.5. Multiplying by 8 gives S - 65 + x = S + 20, so x = 85 kg.

AI explanation

The total increase in weight is calculated by multiplying the number of persons by the increase in the average, so 8 times 2.5 gives a total increase of 20 kg. Since the new person replaces someone weighing 65 kg, the weight of the new person is the old weight plus the total increase, yielding 65 plus 20. The weight of the new person is 85 kg.

Keep practicing — related questions