on 1st jan 2016 sanika decides to save ₹10,11,and on second day ₹12 on third day .if she decides to save like this .then on 31st dec 2016 what would be her total saving ?
Answers
= we have
= 1st January =
10+11+20= 41
then we do this same
so we get = 41 multiply by 41
= ans = 1681
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Answer :
›»› Sanika total saving would be ₹70455 till the end of the year.
Given :
- On 1st jan 2016 sanika decides to save ₹10, ₹11, and on second day ₹12 on third day.
To Find :
- On 31st dec 2016 what would be her total saving ?
Solution :
Sanika saves ₹10 on first day, ₹11 on second day, ₹12 on third day. This is an sequence.
→ 10 + 11 + 12 + ............ + (till 31 december).
The common difference will be,
→ d = a₂ - a₁
→ d = 11 - 10
→ d = 1
Therefore, 10, 11, 12 ..... is an AP.
Here,
- a = 10.
- d = 1.
The year 2016 is a leap year. A leap year has 366 days.
- n = 366.
The total saving in 366 days is s₃₆₆.
As we know that
→ sₙ = n/2 [2a + (n - 1)d]
→ s₃₆₆ = 366/2 [2 * 10 + (366 - 1)1]
→ s₃₆₆ = 183 [2 * 10 + (366 - 1)1]
→ s₃₆₆ = 183 [2 * 10 + 365 * 1]
→ s₃₆₆ = 183 [2 * 10 + 365]
→ s₃₆₆ = 183 [20 + 365]
→ s₃₆₆ = 183 * 385
→ s₃₆₆ = 70455.