MATHEMATICS

JAMB 2012 - Question 20

Mathematics 2012 JAMB Past Questions - Question 20: The sum to infinity of a geometric progression is -1/10 and the first term is -1/8.Find the common ratio of the progression.

The sum to infinity of a geometric progression is -1/10 and the first term is -1/8.Find the common ratio of the progression.
A:
B:
C:
D:
Examkits App

Examkit's JAMB CBT App

Practice JAMB offline with our Online, PC and Mobile App

  • ✅ 25+ years of past questions (2000 to 2025)
  • ✅ Video solutions and explanation to questions
  • ✅ E-library
  • ✅ Study by topic
  • ✅ And more.

Correct Answer

B

Explanation

To find the common ratio (r) of a geometric progression when the sum to infinity is -1/10 and the first term is -1/8, we can use the formula for the sum of an infinite geometric series.The formula for the sum of an infinite geometric series is:S = a / (1 - r)Where S is the sum to infinity, a is the first term, and r is the common ratio.Given that S = -1/10 and a = -1/8, we can substitute these values into the formula:-1/10 = (-1/8) / (1 - r)To simplify the equation, we can multiply both sides by (1 - r):(-1/10)(1 - r) = -1/8Expanding the left side:-1/10 + (1/10)r = -1/8To eliminate the fractions, we can multiply both sides by the least common denominator, which is 40:-4 + 4r = -5Now, let's solve for r:4r = -5 + 44r = -1Dividing both sides by 4:r = -1/4Therefore, the common ratio of the geometric progression is -1/4.

Frequently Asked Questions

Examkits is a JAMB CBT practice platform that provides over 20 years of past questions, Post UTME questions, and detailed video solutions to help students prepare for their exams.

You can practice JAMB past questions online, on Android, or on a desktop using the Examkits app. Just register on our website and choose your preferred device.

Yes. Our Android and Windows versions support offline usage. Once downloaded and activated, no internet is required to use most of the features.

Yes, Examkits provides detailed video explanations for all JAMB past questions from 2000 to 2024, helping students understand how to solve each problem.

Examkits offers free practice for some subjects. However, full access requires a one-time affordable activation fee for each version of the app.