The question is about mean of five terms of an AP. Unarranged five terms of an AP is given and we need to verify the given statements. With some simple but very powerful ideas, one can cut down on a lot of working when it comes to progressions. For example, anchoring a progression around its middle term can be very useful. CAT Exam tests the idea of progression often in the CAT Quantitative Aptitude section and this could also be tested in DI LR section of the CAT Exam as a part of a puzzle.

Question 5: a, b, c, d and e are 5 distinct numbers that from an arithmetic progression. They are not necessarily consecutive terms but form the first 5 terms of the AP. It is known that c is the arithmetic mean of a and b, and d is the arithmetic mean of b anc c. Which of the following statements are true?

i. Average of all 5 terms put together is c.

ii. Average of d and e is not greater than average of a and b.

iii. Average of b and c is greater than average of a and d.

- i and ii only
- ii and iii only
- all three statements are true
- i and iii only

Try upto 40 hours for free

Learn from the best!

Limited Seats Available - Register Now!

I. c is the arithmetic mean of a and b => c lies in between a and b. And it lies exactly in between the two terms. As in the number of terms between a and c should be equal to number of terms between b and c.

a, c, b could be the

1st 2nd and 3rd terms respectively or

1st, 3rd and 5th respectively, or

2nd, 3rd, 4th respectively, or

3rd, 4th, 5th respectively.

The terms could also be the other way around. As in, b, c, a could be the 1st 2nd and 3rd terms respectively, or the 1st, 3rd and 5th respectively, and so on. This is a very simple but very powerful idea.

II. Now, d is the arithmetic mean of b and c. => d lies between b and c. Using statements I and II we can say that a, c, b have to be 1st, 3rd and 5th or 5th, 3rd and 1st as there is an element between b and c also.

**So, c is the third term. a and b are 1st and 5th in some order.**

b ___ c ___ a or a ___ c ___ b

d is the arithmetic mean of b and c.

Possible arrangements are:

b d c e a or a e c d b

The question is **"Which of the given statements are true?"**

Choice A is the correct answer.

CAT 2024

Classroom Batches Starting Now! @Gopalapuram and @Anna nagar

Copyrights © All Rights Reserved by 2IIM.com - A Fermat Education Initiative.

Privacy Policy | Terms & Conditions

CAT^{®} (Common Admission Test) is a registered trademark of the Indian Institutes of Management. This website is not endorsed or approved by IIMs.

2IIM Online CAT Coaching

A Fermat Education Initiative,

58/16, Indira Gandhi Street,

Kaveri Rangan Nagar, Saligramam, Chennai 600 093

**Phone:** (91) 44 4505 8484

**Mobile:** (91) 99626 48484

**WhatsApp:** WhatsApp Now

**Email: **prep@2iim.com