For The Mathematically Inclined

Anil Saigal

The first three terms of an arithmetic sequence are 2x-3, 5x-11 and 3x+1, respectively. The nth term of the sequence is 2009. What is n?

Let a + a x + a x^2 + a x^3 + .... and a + a y + a y^2 + a y^3 + .... be two different infinite geometric series of positive numbers with the same first term. The sum of the first series is x, and the sum of the second series is y. What is x+y?


Please send your solutions to

Use Problem Solutions M-043009 as the subject line. Please include your full name in the text of the main message. Everyone with the right answer will be acknowledged in the next issue of Lokvani.

Please do not post your solution in Post Comments. No credit will be given for solutions not sent to

If you need clarification on any problem, please contact


Problem Solutions 04/16/09


Any given length of highway is equally likely to have as many potholes as any other length of equal size. The average number of potholes per mile of highway is 3. What is the probability that 2 miles of highway have 3 or fewer potholes?

Solution: P(0)+P(1)+P(2)+P(3) using Poisson's Distribution and mean of 6.


Three people (A, B, and C) need to cross a bridge. A can cross the bridge in 10 minutes, B can cross in 5 minutes, and C can cross in 2 minutes. There is also a bicycle available and any person can cross the bridge in 1 minute with the bicycle. What is the shortest time that all men can get across the bridge? Each man travels at his own constant rate

Solution: 5 minutes.

Congratulations to Suhas Joglekar and Muneeba Syed, who were the winner of the last set of puzzles.

Bookmark and Share | Share your Comments

Comments :
Post a new message

You may also access this article through our web-site

Home | About Us | Contact Us | Copyrights Help