In a boat there are 8 men whose average weight is increased by 1 kg when 1 man of 60 kg is replaced by a new man. What is weight of new comer?

8(x+1)-N=8x-60
N=68

I think the unit should be in kg not year as given.

Suppose, the average weight of 8 men before replacement is x, Hence total weight of 8 men would be 8x. Now, let's say the weight of the new man is y. Hence, replacement can be represented with following equation

8x + y - 60 ………(1)

Now, due to replacement, average weight of boat has increases by 1 I.e. x + 1

So, New total weight of the 8 men can be represented by following equation

8(x+1) …………(2)

But equation (1) & (2) are equal, as both of them represents new total weight on boat.

Hence,

8x + y - 60 = 8(x + 1)

8x + y - 60 = 8x + 8

y - 60 = 8

y = 68 kg.

So the weight of the newly added man is 68 kg.

new comer = weight of separated member+(increase in average + members in group)
new comer=60+(1*8)
=68