The best way to go about preparing for the CAT exam is to practice CAT previous year paper questions. They help you understand the pattern and the difficulty level of the questions that you'll face in the CAT Question Paper. Do not stretch yourself to do extremely difficult questions for acing your CAT preparation online, however, it'll be naive of you if you do not practice the questions from CAT previous year paper. Start right away with this question from Progressions taken from CAT 2019 Question Paper.
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Question 29 : If (2n+1) + (2n+3) + (2n+5) + ... + (2n+47) = 5280 , then what is the value of 1+2+3+ ... +n ? [TITA]
Given series - (2n+1) + (2n+3) + (2n+5) + ... + (2n+47) = 5280
Isolate 2n terms on one side
(2n + 2n +.... + 2n) + (1 +3 + 5 +.... + 47) = 5280
Odd numbers from 1 to 47 are added in the above series.
Number of terms from 1 to 47 = 24 terms
Therefore, the number of 2n terms = 24
For computing the value of (1 +3 + 5 +.... + 47),
We know 1 = 12, 1 +3 = 22, 1 +3 +5 = 32 and so on
So, (1 +3 + 5 +.... + 47) = 242
So, 2n x 24 + 242 = 5280
2n x 24 = 5280 - 242
2n = 220 - 24
n = 110 - 12
n = 98
So, value of 1+2+3+...+98 = = =
Value of 1+2+3+...+98 = 4851
The question is "If (2n+1) + (2n+3) + (2n+5) + ... + (2n+47) = 5280 , then what is the value of 1+2+3+ ... +n ? [TITA] "
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