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Arithmetic Progressions

Question
CBSEENMA10007566
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Ramkali saved Rs. 5 in the first week of a year and then increased her weekly savings by Rs. 1.75, if in the nth week, her weekly savings became Rs. 20.75, find n.

Solution

Weekly savings of Ramkali is following :
5, 6.75, 8.50, 10.25............
Here, a = 5, d = 1.75, Tn = 20.75
We know that, Tn = a + (n - 1) d
rightwards double arrow 20.75 = 5 + (n - 1) (1.75)
rightwards double arrow 20.72= 5 + 1.75 n - 1.75
bold rightwards double arrow 20.75 = 1.7n + 3.25
rightwards double arrow  1.75n = 17.5
rightwards double arrow    straight n equals fraction numerator 17.5 over denominator 1.75 end fraction equals 10  
Hence,    n = 10.

Some More Questions From Arithmetic Progressions Chapter

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a – 10, d = 10

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = –2, d = 0

Write first four terms of the AP, when the first term a and the common difference d are given as follows:
a = 4, d = – 3

Write first four terms of the AP, when the first term a and the common difference d are given as follows:

a = – 1.25, d = – 0.25

For the following APs, write the first term and the common difference
3, 1, – 1, – 3, . . .

For the following APs, write the first term and the common difference
– 5, – 1, 3, 7, . . .

For the following APs, write the first term and the common difference
0.6, 1.7, 2.8, 3.9, . . .

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