Advertisements
Advertisements
प्रश्न
In a ‘Mahila Bachat Gat’, Sharvari invested ₹ 2 on first day, ₹ 4 on second day and ₹ 6 on third day. If she saves like this, then what would be her total savings in the month of February 2010?
उत्तर
Amount invested by Sharvari in the month of February 2010 are as follows:
2, 4, 6, .....
The above sequence is an A.P
∴ a = 2, d = 4 – 2 = 2
Number of days in February 2010,
n = 28
Now, Sn = `"n"/2 [2"a" + ("n" - 1)"d"]`
∴ S28 = `28/2 [2(2) + (28 - 1)(2)]`
= 14[4 + 27(2)]
= 14(4 + 54)
= 14(58)
= 812
∴ Total savings of Sharvari in the month of February 2010 is ₹ 812.
APPEARS IN
संबंधित प्रश्न
If Sn denotes the sum of first n terms of an A.P., prove that S30 = 3[S20 − S10]
If the mth term of an A.P. is 1/n and the nth term is 1/m, show that the sum of mn terms is (mn + 1)
Find the sum of all natural numbers between 1 and 100, which are divisible by 3.
The 9th term of an AP is -32 and the sum of its 11th and 13th terms is -94. Find the common difference of the AP.
If the numbers a, 9, b, 25 from an AP, find a and b.
If the ratio of sum of the first m and n terms of an AP is m2 : n2, show that the ratio of its mth and nth terms is (2m − 1) : (2n − 1) ?
The Sum of first five multiples of 3 is ______.
If m times the mth term of an A.P. is eqaul to n times nth term then show that the (m + n)th term of the A.P. is zero.
If the sum of n terms of an A.P. is 3n2 + 5n then which of its terms is 164?
The sum of first 15 terms of an A.P. is 750 and its first term is 15. Find its 20th term.
Find the common difference of an A.P. whose first term is 5 and the sum of first four terms is half the sum of next four terms.
Determine the sum of first 100 terms of given A.P. 12, 14, 16, 18, 20, ......
Activity :- Here, a = 12, d = `square`, n = 100, S100 = ?
Sn = `"n"/2 [square + ("n" - 1)"d"]`
S100 = `square/2 [24 + (100 - 1)"d"]`
= `50(24 + square)`
= `square`
= `square`
Find the sum of natural numbers between 1 to 140, which are divisible by 4.
Activity: Natural numbers between 1 to 140 divisible by 4 are, 4, 8, 12, 16,......, 136
Here d = 4, therefore this sequence is an A.P.
a = 4, d = 4, tn = 136, Sn = ?
tn = a + (n – 1)d
`square` = 4 + (n – 1) × 4
`square` = (n – 1) × 4
n = `square`
Now,
Sn = `"n"/2["a" + "t"_"n"]`
Sn = 17 × `square`
Sn = `square`
Therefore, the sum of natural numbers between 1 to 140, which are divisible by 4 is `square`.
Find the sum of numbers between 1 to 140, divisible by 4
The sum of the first 2n terms of the AP: 2, 5, 8, …. is equal to sum of the first n terms of the AP: 57, 59, 61, … then n is equal to ______.
Find the sum of the integers between 100 and 200 that are
- divisible by 9
- not divisible by 9
[Hint (ii) : These numbers will be : Total numbers – Total numbers divisible by 9]
In the month of April to June 2022, the exports of passenger cars from India increased by 26% in the corresponding quarter of 2021-22, as per a report. A car manufacturing company planned to produce 1800 cars in 4th year and 2600 cars in 8th year. Assuming that the production increases uniformly by a fixed number every year. |
Based on the above information answer the following questions.
- Find the production in the 1st year
- Find the production in the 12th year.
- Find the total production in first 10 years.
[OR]
In how many years will the total production reach 31200 cars?
In an A.P., the sum of first n terms is `n/2 (3n + 5)`. Find the 25th term of the A.P.
The sum of 41 terms of an A.P. with middle term 40 is ______.
The nth term of an A.P. is 6n + 4. The sum of its first 2 terms is ______.
