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 before the Mathematics lecture?

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Last updated 23 May 2026, 3:31 pm IST
  1. AEconomicsCorrect
  2. BHistory
  3. CStatistics
  4. DEnglish

Explanation

Here's a step-by-step breakdown to solve the problem: 1. **Identify the fixed point:** The statement "Guest faculty for History is available only on Tuesday" means History is scheduled for Tuesday. * Schedule so far: * Monday: * Tuesday: History * Wednesday: * Thursday: * Friday: 2. **Identify the block of consecutive lectures:** * "Mathematics lecture has to be scheduled immediately after the day of Economics lecture" (E -> M) * "English lecture has to be scheduled immediately before the day of Economics lecture" (En -> E) * Combining these, we get a block of three consecutive lectures: English -> Economics -> Mathematics (En-E-M). 3. **Place the En-E-M block:** * This block needs three consecutive days. * We know Tuesday is History. * Economics cannot be on Tuesday. * Possible slots for En-E-M: * Monday, Tuesday, Wednesday: Not possible, as Tuesday is History. * Tuesday, Wednesday, Thursday: Not possible, as Tuesday is History and Economics cannot be on Tuesday. * Wednesday, Thursday, Friday: This is the only possible slot. 4. **Complete the schedule:** * Monday: * Tuesday: History * Wednesday: English (from En-E-M block) * Thursday: Economics (from En-E-M block) * Friday: Mathematics (from En-E-M block) * The remaining subject is Statistics, which must be on Monday. * Final Schedule: * Monday: Statistics * Tuesday: History * Wednesday: English * Thursday: Economics * Friday: Mathematics 5. **Answer the question:** "Which lecture is scheduled before the Mathematics lecture?" * Mathematics is scheduled on Friday. * The lecture immediately before it, on Thursday, is Economics. Therefore, Economics is scheduled before the Mathematics lecture. The final answer is A) Economics.
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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