A manufacturer of TV sets produced 6000 units in the third year and 7000 units in the seventh year. Assuming that the production increases uniformly by a fixed number every year, find the production
(i) in the first year,
(ii) in the 10th year,
(iii) in 7 years.
Hint: - In the question it is mentioned that the production increases by a fixed number every year.
So it is an A.P. (a1, a2, a3, a4, ........an - 1, an).
Given: -
The 3rd year production is 6000 units
So,
a3 = 6000
We know that an = a + (n - 1) ×d
a3 = a + (3 - 1)×d
6000 = a + 2d
The 7th year production is 7000 units
So,
a7 = 7000
a7 = a + (7 - 1)×d
7000 = a + 6d
From equations (1)&(2) we get,
6000 - 2d = 7000 - 6d
4×d = 1000
d = 250
From equations (1)&(2) we get,
a = 5500
i. Production in the first year = a = 5500
∴5500 units were produced by the manufacturer of TV sets in the first year.
ii. Production in the 10th year = a10 = a + (10 - 1)×d
a10 = 5500 + (9) ×250
= 7750
∴7750 units were produced by the manufacturer of TV sets in the 10th year.
iii. Total production in seven years = a1 + a2 + a3 + a4 + a5 + a6 + a7
s7 = 43750
∴A total of 16, 250 units was produced by the manufacturer in 7 years.