Find the 12th term of a G.P. whose | Class 11 Mathematics Chapter Sequence and Series, Sequence and Series NCERT Solutions

Question:

Find the 12th term of a G.P. whose 8th term is 192 and the common ratio is 2.

Answer:

Common ratio, r = 2

Let a be the first term of the G.P.

∴ a8 = ar 8–1 = ar7

⇒ ar7 = 192

a(2)7 = 192

a(2)7 = (2)6 (3)

rightwards double arrow a equals fraction numerator open parentheses 2 close parentheses to the power of 6 cross times 3 space over denominator open parentheses 2 close parentheses to the power of 7 end fraction equals 3 over 2
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a subscript 12 space equals a r to the power of 12 minus 1 end exponent space equals space open parentheses 3 over 2 close parentheses open parentheses 2 close parentheses to the power of 11 equals open parentheses 3 close parentheses open parentheses 2 close parentheses to the power of 10 equals 3072

 


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Comments

  • RUPAM BANERJEE
  • 2017-03-11 12:21:14

S.I. for 1 year = Rs. (2124-2016) = Rs. 108. S.I. for 2 years = Rs.(108 x 2) = Rs. 216. We know that, A = P + S.I. So, A = 2016 S.I. = 216 Principal, P = Rs. (2016-216) = Rs. 1800.


  • Kavya Gowda
  • 2017-02-23 11:19:17

A sum of money becomes ` 2016 in 2 years and ` 2124 in 3 years, at simple interest. What is the sum of money? Ans: sum of money p= 1800


  • kanjibhai
  • 2017-02-22 21:06:12

A sum of money becomes ` 2016 in 2 years and ` 2124 in 3 years, at simple interest. What is the sum of money?


  • kanjibhai
  • 2017-02-22 21:05:13

The ratio of 12th term to 15th term of a G.P. is 8 : 1. What is the common ratio of G.P?


  • Jas
  • 2016-09-01 19:26:37

Good answer


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 11 Mathematics - Chapter . This page offers a step-by-step solution to the specific question from Excercise 3 , Question 2: Find the 12th term of a G.P. whose 8th term is 192 and the common ratio is 2.....