Question

22. A manufacturer of t v sets produced 60 sets in
the third year and 700 sets in the 7thyear .Assuming
that the production increases uniformly by a fixed
number every year find 1) the production in the 1st
year. 2) the production in the 10th year. 3) the total
production in 7 years.?
Sol:​

Answer 1

Step-by-step explanation:

i) Production in third year = 60 sets

Production in seventh year = 700 sets

↪ a + 2d = 60 -----------> 1

a + 6d = 700 ---------> 2

Subtracting 1 from 2

↪ a + 6d - a -2d = 700 - 60

4d = 640

d = 160

Putting value of d in eq. 1

↪ a + 2( 160) = 60

a + 320 = 60

a = 60 - 320

a = - 260 sets

ii) The production in 10th year:

an = a + (n-1) d

a10 = -260 + (10 - 1) × 160

a10 = -260 + (9 × 160)

a10 = -260 + 1440

↪ a10 = 1180 sets

iii) The total production in 7 years:

↪ $Sn = \frac{n}{2} \times(2a + (n - 1) \times d) \\ S10 = \frac{10}{2} \times (2 \times - 260 + (10 - 1) \times 160) \\ S10 = 5 \times ( - 520 + 1440) \\ S10 = 5 \times 920 \\ ↪ S10 = 4600 \: sets$

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Answer 2

Answer:

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