UPSC Prelims 2016 · CSAT
Question 53: Basic Numeracy
A person is standing on the first step from the bottom of a ladder. If he has to climb 4 more steps to reach exactly the middle step, how many steps does the ladder have ?
AnswerUPSC’s answer is (b).
He stands on step 1 and climbs 4 more steps to reach the middle, so the middle step is step 5. A ladder with step 5 exactly in the middle has 4 steps below it and 4 above: 4 + 1 + 4 = 9 steps. Remember: the middle of an odd count has equal numbers on both sides.
How you could have got this
No shortcut here: in a “how many” question, ruling out options doesn’t help. Every statement has to be judged.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) 8 steps has no single middle step.
- (b) Right: step 5 has 4 steps below and 4 above.
- (c) 10 steps has no single middle step.
- (d) 11 steps has middle step 6, which is 5 climbs from step 1.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2016, General Studies Paper II (CSAT), Series A. The paper on upsc.gov.in.