मराठी

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 week, her weekly savings become Rs 20.75, find n.

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प्रश्न

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 week, her weekly savings become Rs 20.75, find n.

बेरीज
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उत्तर

Given that,

a = 5

d = 1.75

an = 20.75

n = ?

an = a + (n − 1) d

⇒ 207.50 = 50 + (n - 1) (17.5)

⇒ 207.50 = 50 + 17.5n - 17.5

⇒ 17.5n = 207.50 + 17.5 - 50

⇒ 17.5n = 225 - 50

⇒ 17.5n = 175

⇒ n = `175/17.5`

⇒ n = 10

Hence, n is 10.

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