This is the basic and conceptual question from Chapter name- Arithmetic Progression

Chapter number- 9

Exercise 9.6

In this question we have been given that Ramkali would need Rs. 1800 for admission fee and books etc.,for her daughter to start going to school from the next year.

She saved Rs. 50 in the first month of this year and increased her monthly saving by Rs. 20.

Now we have to find that after a year, how much money will she save

Also we have to find out if she will be able to fulfill her dream of sending her daughter to school.

CBSE DHANPAT RAI publications

Class:- 10th

Solutions of CBSE Mathematics

Question 62

Given that Ramkali has saved in following sequence in a year(every month record): 50, 70, 90,. . . .

First term(a) = 50 and common difference(d) = 20.

Now by using the formula of the sum of n terms of an A.P.

Sn = n[2a +(n – 1)d] / 2

So,

Now, sum of the savings after 1 year(12 months) would be S12 as value of n in this case is 12.

S12 = 12[2(50) + (12 – 1)20] / 2

= 6[100 + 220]

= 6[320]

= 1920

Hence, Resham would save Rs 1920 by the end of 1 year(12 months) which is

greater than Rs 1800, she would be able to fulfill her dream of sending her daughter to school.