Question

The average weight of 8 persons is increased
by 2.5 kg, when one of them whose weight is
56 kg is replaced by a new man. The weight
of the man is​

Answer 1

Answer:

76

okay its simple..look.

When a new person of joins the group by replacing someone it increases the average weight by 2.5. In other words he is increasing everyone’s relative weight by 2.5 including himself…

so 2.5 * 8 =20 is the additional weight added to the group.

the person who left was 56 and new person brings 20 more. so 76 is the weight of the new person.

Alternative method-

let the average earlier be x.

then the sum of weight of all 8 people will be 8x.

now new person replaces a person and average becomes x+2.5 (new average)

the total number of persons are still 8, so new total of weights of all 8 people will be now 8(x+2.5) = 8x+20.

okay so earlier the total weight of all 8 people was 8x but as soon as a new person replaced a person of 65 (weight) the total becomes 8x+20 which is 20 more than the previous total….he must be 20 more than 56 i.e 76

Hope this helps