Advertisements
Advertisements
प्रश्न
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
उत्तर
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
संबंधित प्रश्न
If Sn denotes the sum of first n terms of an A.P., prove that S30 = 3[S20 − S10]
How many multiples of 4 lie between 10 and 250?
Determine the A.P. whose 3rd term is 16 and the 7th term exceeds the 5th term by 12.
Find the sum of all integers between 84 and 719, which are multiples of 5.
Find the middle term of the AP 6, 13, 20, …., 216.
Write the next term for the AP` sqrt( 8), sqrt(18), sqrt(32),.........`
Find the sum of all natural numbers between 200 and 400 which are divisible by 7.
Choose the correct alternative answer for the following question .
If for any A.P. d = 5 then t18 – t13 = ....
For what value of n, the nth terms of the arithmetic progressions 63, 65, 67, ... and 3, 10, 17, ... equal?
The sum of the first n terms of an A.P. is 3n2 + 6n. Find the nth term of this A.P.
If the sum of n terms of an A.P. is 3n2 + 5n then which of its terms is 164?
The first three terms of an A.P. respectively are 3y − 1, 3y + 5 and 5y + 1. Then, y equals
Find the sum of first 10 terms of the A.P.
4 + 6 + 8 + .............
If the third term of an A.P. is 1 and 6th term is – 11, find the sum of its first 32 terms.
The sum of first n terms of the series a, 3a, 5a, …….. is ______.
Yasmeen saves Rs 32 during the first month, Rs 36 in the second month and Rs 40 in the third month. If she continues to save in this manner, in how many months will she save Rs 2000?
Complete the following activity to find the 19th term of an A.P. 7, 13, 19, 25, ........ :
Activity:
Given A.P. : 7, 13, 19, 25, ..........
Here first term a = 7; t19 = ?
tn + a + `(square)`d .........(formula)
∴ t19 = 7 + (19 – 1) `square`
∴ t19 = 7 + `square`
∴ t19 = `square`
Find the middle term of the AP. 95, 86, 77, ........, – 247.
Find the sum of first 20 terms of an A.P. whose nth term is given as an = 5 – 2n.
