# Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the n^{th} week, her weekly savings become Rs 20.75, find n

**Solution:**

a_{n} = a + (n - 1)d is the nth term of AP.

Here, a is the first term, d is a common difference and n is the number of terms.

From the given data, Ramkali’s savings in the consecutive weeks are Rs 5, Rs (5 + 1.75), Rs (5 + 2 × 1.75), Rs (5 + 3 × 1.75) ... and so on

Hence, in n^{th} weeks savings, Rs [5 + (n - 1) × 1.75] = Rs 20.75

According to the question, we have a = 5, d = 1.75, a_{n} = 20.75

We know that the nth term of AP is a_{n} = a + (n - 1)d

20.75 = 5 + (n - 1)1.75

15.75 = (n - 1)1.75

(n - 1) = 15.75/1.75

n - 1 = 1575/175

n - 1 = 9

n = 10

Answer: So, in the 10th week Ramkali's saving will be Rs 20.75

**Video Solution:**

## Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the n^{th} week, her weekly savings become Rs 20.75, find n

### Class 10 Maths NCERT Solutions Chapter 5 Exercise 5.2 Question 20 - Chapter 2 Exercise 5.2 Question 20:

Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the n^{th} week, her weekly savings become Rs 20.75, find n

The value of n is 10 if Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the n week, her weekly savings become Rs 20.75