UPSC Prelims 2012·CSAT·Logical Reasoning·Arrangement and Puzzles

Examine the information given in the following paragraph and answer the items that follow: Guest lectures on five subjects viz., Economics, History, Statistics, English and Mathematics have to be arranged in a week from Monday to Friday. Only one lecture can be arranged on each day. Economics cannot be scheduled on Tuesday. Guest faculty for History is available only on Tuesday. Mathematics lecture has to be scheduled immediately after the day of Economics lecture. English lecture has to be scheduled immediately before the day of Economics lecture. Which lecture is scheduled on Monday?

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Last updated 23 May 2026, 3:31 pm IST
  1. AHistory
  2. BEconomics
  3. CMathematics
  4. DStatisticsCorrect

Explanation

Here's a step-by-step breakdown: 1. "Guest faculty for History is available only on Tuesday." This immediately sets Tuesday = History. 2. "Mathematics lecture has to be scheduled immediately after the day of Economics lecture." (E -> M) 3. "English lecture has to be scheduled immediately before the day of Economics lecture." (En -> E) Combining these two, we get a block of three consecutive lectures: English -> Economics -> Mathematics (En -> E -> M). Now, let's place these on the schedule (Monday to Friday): Monday | Tuesday | Wednesday | Thursday | Friday | History | | | The block (En -> E -> M) needs three consecutive days. Since Tuesday is already taken by History, this block cannot start on Monday (as E would be Tuesday, conflicting with History). Therefore, the block must start on Wednesday. So, the schedule becomes: Monday | Tuesday | Wednesday | Thursday | Friday | History | English | Economics | Mathematics We have used History, English, Economics, and Mathematics. The only remaining subject is Statistics. The only remaining day is Monday. Therefore, Monday = Statistics. Final schedule: Monday: Statistics Tuesday: History Wednesday: English Thursday: Economics Friday: Mathematics All conditions are met: - History is on Tuesday. - Economics is not on Tuesday. - Mathematics is immediately after Economics. - English is immediately before Economics. The lecture scheduled on Monday is Statistics. The final answer is D) Statistics.
Logical Reasoning: Examine the information given in the following paragraph and answer the items that follow: Guest lectures on five subjec

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