Advertisements
Advertisements
Question
Shubhankar invested in a national savings certificate scheme. In the first year he invested ₹ 500, in the second year ₹ 700, in the third year ₹ 900 and so on. Find the total amount that he invested in 12 years
Advertisements
Solution
Amount invested by Shubhankar in the national savings certificate scheme is as follows:
500, 700, 900, ......
The above sequence is an A.P.
∴ a = 500, d = 700 – 500 = 200, n = 12
Now, Sn = `"n"/2 [2"a" + ("n" - 1)"d"]`
∴ S12 = `12/2 [2(500) + (12 - 1)(200)]`
= 6[1000 + 11(200)]
= 6(1000 + 2200)
= 6(3200)
= 19200
∴ The total amount invested by Shubhankar is ₹ 19,200.
APPEARS IN
RELATED QUESTIONS
Divide 32 into four parts which are in A.P. such that the product of extremes is to the product of means is 7 : 15.
The sum of n, 2n, 3n terms of an A.P. are S1 , S2 , S3 respectively. Prove that S3 = 3(S2 – S1 )
In an AP, given a = 2, d = 8, and Sn = 90, find n and an.
Find the sum of first n odd natural numbers
Find the sum of the first 51 terms of the A.P: whose second term is 2 and the fourth term is 8.
Find the sum of all 3 - digit natural numbers which are divisible by 13.
If numbers n – 2, 4n – 1 and 5n + 2 are in A.P., find the value of n and its next two terms.
Find the sum of first 12 natural numbers each of which is a multiple of 7.
Determine k so that (3k -2), (4k – 6) and (k +2) are three consecutive terms of an AP.
The fourth term of an A.P. is 11. The sum of the fifth and seventh terms of the A.P. is 34. Find its common difference.
Write an A.P. whose first term is a and common difference is d in the following.
In an A.P., the first term is 22, nth term is −11 and the sum to first n terms is 66. Find n and d, the common difference
The sum of the first 7 terms of an A.P. is 63 and the sum of its next 7 terms is 161. Find the 28th term of this A.P.
Write the value of x for which 2x, x + 10 and 3x + 2 are in A.P.
If the first term of an A.P. is a and nth term is b, then its common difference is
Two A.P.'s have the same common difference. The first term of one of these is 8 and that of the other is 3. The difference between their 30th term is
If k, 2k − 1 and 2k + 1 are three consecutive terms of an A.P., the value of k is
The sum of the first 15 multiples of 8 is ______.
Find the value of a25 – a15 for the AP: 6, 9, 12, 15, ………..
