What is the sum of the first 10 terms of the series?
1, 3, 5, 7, ...?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 100.
Given Series: 1, 3, 5, 7, ...
Number of terms (n) = 10
First term (a) = 1
Common difference (d) = 2
Sum of n terms = n + 2 × [2a + (n - 1)d]
Sum = 10 + 2 × [2 × 1+ (10 - 1) × 2]
⇒ Sum = 5 × [2 + 18]
⇒ Sum = 5 × 20
⇒ Sum = 100
Thus, the sum of the first 10 terms is 100.