Question

Kanika was given her pocket money on January 1st 2008 she put Rupees 1 on day 1, 2 on Day 2 and rupees 3 on day 3, and continue doing so till the end of the month from this money into her piggy bank, also spend rupees 204 of a pocket money and at the end of the month that she still had rupees hundred with her. How much was her pocket money for the month ?

Answer 1

In a month of Jan , there are 31 days

First term = 1 , Difference = 1

Sum = n / 2 [ 2a + (n - 1)d]

Sum = 31 / 2 [ 2 * 1 + (31 - 1)(1) ]

Sum = 31 / 2 [ 2 + 30 ]

Sum = (31 / 2) * 32

Sum = 31 * 16

Sum = 496

Now this Rs 496 has been put into piggy bank from the pocket money

Let the pocket money be x , also she spent Rs 204 ,Amount Remaining = 100

So , x - 496 - 204 = 100

x - 700 = 100

x = 800

Ans: Rs 800