CA Foundation P3 · Chapter 6 · Question 6 of 9
The sum of the first 6 terms of the G.P. 2, 6, 18, ... is:
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: C) 728
Explanation
a = 2, r = 3. S₆ = a(rⁿ − 1)/(r − 1) = 2(3⁶ − 1)/2 = 729 − 1 = 728. 486 is the 6th term, and 364 forgets that the factor a = 2 cancels with (r − 1) = 2.
More Sequence and Series - Arithmetic and Geometric Progressions MCQs
- 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:
- Q1The 15th term of the A.P. 7, 11, 15, 19, ... is:
- Q2The sum of the first 20 terms of the A.P. 3, 8, 13, ... is:
- Q3How many terms of the A.P. 5, 9, 13, ... must be taken so that their sum is 230?