Question

Kanika was given her pocket money on Jan. 1, 2008. She puts ₹ 1 on day 1, ₹ 2 on day 2, ₹ 3 on day 3, and continued doing so till the end of the month, from this money into her piggy bank. She also spent ₹ 204 of her pocket money, and found that at the end of the month she still had ₹ 100 with her. How much was her pocket money for the month

 

 

 

class x arithmatic progressions

Answer 1

Total savings = 1+2+3+...+31=(1+31)+(2+30)+(3+29)+...+(15+17)+16=15×32+16=₹496.

Add ₹204 and we have ₹700 and the ₹100 remaining makes ₹800 in total.