Question

The average weight of a certain number of persons in a group is 78 kg. If 4 persons having average weight 80.75 kg leaves the group, the average weight of the remaining persons becomes 77.725 kg. The number of persons initially is:
1. 36
2. 44
3. 46
4. 34

Answer 1

Correct Answer - Option 2 : 44

Given:

Average weight of number of person = 78kg.

Average weight of remaining persons = 77.725 years.

Concept Used:

Average weight of number of person - Average weight of 4 persons = Average weight of remaining persons

Calculation:

Let the number of persons be x.

then, Total weight of number of person = (78x)

Total weight of remaining persons = 77.725 (x – 4)

Average weight of 4 person = 80.75kg × 4 = 323 kg

Average weight of number of person - Average weight of 4 persons = Average weight of remaining persons

⇒ 78x – 323 = 77.725(x - 4)

⇒ 78x – 323 = 77.725x – 310.9

⇒ 78x – 77.725x = 323 – 310.9

⇒ 0.275x = 12.1

⇒ x = 12.1/0.275

⇒ x = 44

∴ The number of persons initially is 44.