In the new year, Dev saved Rs. 50 in the first week and then increased his weekly savings by Rs. 17.50. If his weekly savings in the nth week become Rs. 207.50, then find the value of n.

Explanation

Savings of the first week (a) = Rs. 50 Common difference (d) = Rs. 17.50 From Tn = a + (n –1) d According to the question, 207.50 = 50 + (n –1) 17.5 $$ \frac{157.5}{17.5} = n - 1 $$ n – 1 = 9 n = 9 + 1 $\Rightarrow$ n = 10