CA Foundation P3 · Chapter 6 · Question 3 of 9
How many terms of the A.P. 5, 9, 13, ... must be taken so that their sum is 230?
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: C) 10
Explanation
Sₙ = n/2 [10 + 4(n − 1)] = n(2n + 3) = 230. So 2n² + 3n − 230 = 0, giving n = [−3 + √(9 + 1840)]/4 = (−3 + 43)/4 = 10. Check: 10 x 23 = 230.
More Sequence and Series - Arithmetic and Geometric Progressions MCQs
- Q5The sum to infinity of the G.P. 12, 4, 4/3, ... is:
- Q6The sum of the first 6 terms of the G.P. 2, 6, 18, ... is:
- Q7Three numbers in A.P. have sum 27 and product 504. The largest of the numbers is:
- Q8The arithmetic mean and geometric mean of two positive numbers are 25 and 15 respectively. The numbers are:
- Q9The sum of the first n terms of the series 0.7 + 0.77 + 0.777 + ... is: