Q20 of 49 Page 105

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

Here, a = 5, d = 1.75 and an = 20.75


We know, an = a + (n -1)d


20.75 = 5 + (n – 1)1.75


(n – 1)1.75 = 20.75 – 5


(n – 1)1.75 = 15.75


n – 1 = 15.75/1.75 = 9


n = 10


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