The average age of a group of workers is 42 years. If 8 new workers with an average age of 36 years join, the average becomes 40 years. Find the number of workers initially present in the group.

There were 16 workers initially.

Let n be the initial count with average 42.

Total age = 42n + 8 x 36 after the new workers join.

New average: (42n + 288) / (n + 8) = 40.

42n + 288 = 40n + 320, so 2n = 32 and n = 16.