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Ex 5.2, 20 - Ramkali saved Rs 5 in the first week of - Statement questions - nth term

  1. Chapter 5 Class 10 Arithmetic Progressions
  2. Serial order wise
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Ex 5.2 ,20 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. Saving made first week = 5 Saving made in second week = 5 + 1.75 = 6.75 Saving made in third week = 6. 75 + 1.75 = 8.50 So, the series is 5, 6.75, 8.50 …… Since difference is same, it is an AP Common difference = d = 1.5 Given, in nth week, her savings become Rs 20.75 So, an = 20.75 Also, a = 5 , d = 1.75 We need to find n Putting these in formula an = a + (n – 1) d 20.75 = 5 + (n – 1) × 1.75 20.75 – 5 = (n – 1) × 1.75 15.75 = (n – 1) × 1.75 15.75/1.75 = n – 1 1575/175 = n – 1 9 = n – 1 n – 1 = 9 n = 9 + 1 n = 10 Hence, in 10th week, her weekly savings become Rs 20.75

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Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.
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