IPMAT Indore 2026 · Quantitative Ability · Question 8
IPMAT Indore 2026 previous year question on Sequences and Series, with the answer and a step-by-step solution.
Let S denote an arithmetic progression whose first term is either 132 or 158, and the common difference is an even integer less than 10. If the {n}^{th} term of S is 174, then the number of possible distinct values of n is ____
Answer & solution
Answer: 5
Step 1 — write the condition. With first term a and common difference d:
a+\left( n-1 \right)d=174 \Rightarrow \left( n-1 \right)d=174-a
Since 174>a in both cases, d must be positive; the even positive values below 10 are d\in \{2,4,6,8\}.
Step 2 — case a=132. Then \left( n-1 \right)d=42:
|
d |
42/d |
n |
|---|---|---|
|
2 |
21 |
22 |
|
4 |
10.5 |
not an integer |
|
6 |
7 |
8 |
|
8 |
5.25 |
not an integer |
Step 3 — case a=158. Then \left( n-1 \right)d=16:
|
d |
16/d |
n |
|---|---|---|
|
2 |
8 |
9 |
|
4 |
4 |
5 |
|
6 |
2.67 |
not an integer |
|
8 |
2 |
3 |
Step 4 — collect the distinct values.
n\in \{22, 8, 9, 5, 3\}\Rightarrow 5\text{values}
Answer: 5
Shortcut. This is a divisor hunt, not an AP question: you need d to divide 174-a. So compute 42 and 16, then just ask which of 2,4,6,8 divide each. Two divisors for 42, three for 16.
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