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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?
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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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