Question

If the sum of the first 40 terms of the series, 3 + 4 + 8 + 9 + 13 + 14 + 18 +19 +… is (102)m, then m is equal to :

(1) 20

(2) 5

(3) 10

(4) 25

Answer 1

Answer is (1)

Sum of the 40 terms of

3 + 4 + 8 + 9 + 13 + 14 + 18 + 19…

= (3 + 8 + 13 +…upto 20 term)

• [4 + 9 + 15 +… upto 20 terms]

= 10 [{6 + 19 × 5} + {8 + 19 × 5}]

= 10 × 204 = 20 × 102