Ramesh was counting down starting from 31. Sumit was counting straight…
2022
Ramesh was counting down starting from 31. Sumit was counting straight starting from 1 and he was saying only odd numbers. If they were speaking at the same speed, what same number would they say together?
Answer: C. 21 — Approach: find the step at which both say the same number. Let k be the step number (k = 1 for the first number they say). Ramesh at step k says 31 - (k - 1).…
- A.
19
- B.
17
- C.
21
- D.
23
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Show answer & explanation
Correct answer: C
Approach: find the step at which both say the same number.
Let k be the step number (k = 1 for the first number they say).
Ramesh at step k says 31 - (k - 1).
Sumit at step k says 1 + 2·(k - 1) = 2k - 1.
Set them equal: 31 - (k - 1) = 2k - 1. This simplifies to 32 - k = 2k - 1 → 33 = 3k → k = 11.
The number they both speak at k = 11 is 31 - (11 - 1) = 31 - 10 = 21.
Check: Sumit says 2·11 - 1 = 21 and Ramesh says 31 - 10 = 21, so both speak 21 together.
Answer: 21