Question 36 (iii) (B)

(iii) (B) The shopkeeper added 3 jars in each layer. How many jars are there in the 5th layer from the top?

 

 

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Question 36 [Case Based] Ms. Sheela visited a store near her house and found that the glass jars are arranged one above the other in a specific pattern. On the top layer there are 3 jars. In the next layer there are 6 jars. In the 3rd layer from the top there are 9 jars and so on till the 8th layer. The jars look like Question 36 (iii) (B) (iii) (B) The shopkeeper added 3 jars in each layer. How many jars are there in the 5th layer from the top?Previous AP was 3, 6, 9, …. After adding 3 jars in each layer, AP is 3 + 3, 6 + 3, 9 + 3, …. 6, 9, 12,…. So, First term = a = 6 Common difference = d = 9 − 6 = 3 We need to find how many jars are there in 5th layer from top i.e. we need to find a5 Now, an = a + (n − 1)d Putting n = 5, a = 6, d = 3 = 6 + (5 − 1) × 3 = 6 + 4 × 3 = 6 +12 = 18 Thus, there are 18 jars in the 5th layer

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.