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Question
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?
Solution
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.
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