CA Foundation P3 Ā· Chapter 6 Ā· Question 2 of 9
The sum of the first 20 terms of the A.P. 3, 8, 13, ... is:
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: A) 1010
Explanation
Sā = n/2 [2a + (n ā 1)d] = 20/2 x [6 + 19 x 5] = 10 x 101 = 1,010. Using 20 instead of 19 gives 10 x 106 = 1,060, and 98 is the 20th term.
More Sequence and Series - Arithmetic and Geometric Progressions MCQs
- Q4The 8th term of the G.P. 3, 6, 12, 24, ... is:
- 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: