Question

Find the sum of the following APs:

0.6, 1.7, 2.8, ... to 100 terms. 

Answer 1

0.6, 1.7, 2.8, ... to 100 terms

For this A.P.,

a = 0.6

d = a₂ – a₁

= 1.7 – 0.6

d = 1.1

n = 100

We know that

S_n = `n/2[2a + (n - 1)d]`

S₁₀₀ = `100/2[2(0.6) + (100 - 1)1.1]`

= 50[1.2 + (99) × (1.1)]

= 50[1.2 + 108.9]

= 50[110.1]

= 5505

Thus, the required sum of first 100 terms is 5505.