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.

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# 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

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

Hence,

First term, a = 5

and common difference, d = 1.75

Also given,

a= 20.75_{n }Find, n = ?

As we know, by the n

^{th}term formula,a=_{n}a+(n−1)dTherefore,20.75 = 5+(

n-1)×1.7515.75 = (

n-1)×1.75(

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

n-1 = 9n= 10Hence,

nis 10.