In arithmetic progressions of exercise of 5.2 of class 10th of math, how i solve the problem of this problem in easy way Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the nth week, her weekly savings become Rs 20.75, find n.

AnilSinghBoraGuru

# Ramkali saved Rs 5 in the first week of a year and then increased her weekly saving by Rs 1.75. If in the nth week, her weekly savings become Rs 20.75, find n. Q.20

Share

Given that, Ramkali saved Rs.5 in first week and then started saving each week by Rs.1.75.

Hence,

First term, aÂ = 5

and common difference, dÂ = 1.75

Also given,

a= 20.75_{nÂ }Find, nÂ = ?

As we know, by the n

^{th}term formula,aÂ =Â_{n}a+(nâˆ’1)dTherefore,20.75 = 5+(

nÂ -1)Ã—1.7515.75 = (

nÂ -1)Ã—1.75(

nÂ -1) = 15.75/1.75 = 1575/175= 63/7 = 9

nÂ -1 = 9nÂ = 10Hence,Â

nÂ is 10.