(Q9).A manufacturer of TV sets produced 600 sets in the third year and 700 sets in the seventh year. Assuming that the production increases uniformly by a fixed number every year, find :

(i) the production in the 1st year

Since the production increases uniformly by a fixed number every year, the number of TV sets manufactured in 1st, 2nd, 3rd, . . ., years will form an AP.

Let us denote the number of TV sets manufactured in the nth year by an.

Then, a3 = and a7 =

or, a + d =

and a + d =

Solving these equations, we get d = and a = .

Therefore, production of TV sets in the first year is .