1. Soft Skills Courses
  2. PMT-101
  3. Unit-6
unit-6-counting-without-counting

Unit-6 Counting Without Counting

In this unit you will learn about Arithmetic Progression, Geometric Progression and other sequences.

The 2 nd and 5 th terms of a GP are 10 and 1250. Find the first term and the common ratio of the GP





< Back To All Answers

Answer

Written on {{ansDate()}}

Learning Pundits Content Team

Written on Apr 23, 2019 11:30:29 AM

Suppose the first term is a and the common ratio is r. The second term is ar. Similarly, the 5 th term is ar^4 . We have

5th term/2 nd term = ar^4/ar = 1250/10 i.e.r^3 = 125 = 5 × 5 × 5 (∴ r = 5) .

So, the common ratio r is 5. Let us now find a. We have 10 = ar = 5a since r = 5. Thus, a = 2