# CAT 2018 Question Paper | Quants Slot 2

###### CAT Previous Year Paper | CAT Sequence and Series Questions | Question 5

The best questions to practice for CAT Exam are the actual CAT Question Papers. 2IIM offers you exactly that, in a student friendly format to take value from this. If you would like to take the same inside a testing engine (for Free) head out here: CAT Official Question Mocks. In CAT 2018 we saw some beautiful questions that laid emphasis on Learning ideas from basics and being able to comprehend more than remembering gazillion formulae and shortcuts. Original CAT Question paper is the best place to start off your CAT prep practice. This page provides exactly that. To check out about 1000 CAT Level questions with detailed video solutions for free, go here: CAT Question Bank

Question 5 :Let t1, t2,.....be real numbers such that t1+ t2 +... + tn = 2n2 + 9n + 13, for every positive integer n ≥ 2. If tk=103, then k equals[TITA]

## Best CAT Coaching in Chennai

#### CAT Coaching in Chennai - CAT 2021Online Batches Available Now!

##### Method of solving this CAT Question from Sequence and Series

Let t1, t2,.....be real numbers such that t1+ t2 +... + tn = 2n2 + 9n + 13
If tk = 103 we have to find the value of k.
Let us assume this as sum to n terms i.e.
Sn = t1+ t2 +... + tn = 2n2 + 9n + 13
Given an expression in terms of n we can also take sum to n-1 terms i.e.
Sn-1 = t1+ t2 +... + tn-1 = 2(n-1)2 + 9(n-1) +13
This Sn and Sn-1 can be subtracted one from the another such that,
Sn = t1+ t2 +... + tn = 2n2 + 9n + 13
Sn-1 = t1+ t2 +... + tn-1 = 2(n-1)2 + 9(n-1) +13
Sn - Sn-1 = tn = 2n2 + 9n + 13 - 2(n-1)2 - 9(n-1) - 13
Sn - Sn-1 = tn = 2n2 + 9n + 13 - 2(n-1)2 - 9n + 9 - 13
Sn - Sn-1 = tn = 2[n2 - (n-1)2] + 9
Sn - Sn-1 = tn = 2[n2 - n2 + 2n - 1] + 9

tn = 2[2n - 1] + 9
tn = 4n - 2 + 9
tn = 4n + 7
So tk = 4k + 7 = 103
k = $$frac{103 - 7}{4}$ k = 24 The 24th term is 103 The question is "Let t1, t2,.....be real numbers such that t1+ t2 +... + tn = 2n2 + 9n + 13, for every positive integer n ≥ 2. If tk=103, then k equals [TITA] " ##### Hence, the answer is 24 ###### ⏰ Fabulous 3,000 off on Green and Crash course Valid until 28th Sep. ###### Best CAT Online Coaching Try upto 40 hours for free Learn from the best! ###### Best Indore IPM & Rohtak IPM CoachingSignup and sample 9 full classes for free. Register now! ###### Already have an Account? ###### CAT Coaching in ChennaiCAT 2021Enroll at 49,000/- 44,000/- Online Classroom Batches Starting Now! ###### Best CAT Coaching in ChennaiPrices slashed by Rs 4000/- Attend a Demo Class ##### Where is 2IIM located? 2IIM Online CAT Coaching A Fermat Education Initiative, 58/16, Indira Gandhi Street, Kaveri Rangan Nagar, Saligramam, Chennai 600 093 ##### How to reach 2IIM? Phone:$91) 44 4505 8484
Mobile: (91) 99626 48484
WhatsApp: WhatsApp Now
Email: prep@2iim.com