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 between Statistics and English?

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  1. AEconomics
  2. BHistoryCorrect
  3. CMathematics
  4. DNo lecture

Explanation

Here's a step-by-step deduction of the schedule: 1. "Guest faculty for History is available only on Tuesday." This immediately fixes History's position: Tuesday: History 2. We have a block of three consecutive lectures: "English lecture has to be scheduled immediately before the day of Economics lecture" and "Mathematics lecture has to be scheduled immediately after the day of Economics lecture." This means the sequence is English -> Economics -> Mathematics (E-E-M). 3. This E-E-M block needs three consecutive days. Let's look at the available slots, keeping in mind Economics cannot be on Tuesday (given) and History is on Tuesday. * Monday-Tuesday-Wednesday: Not possible because History is on Tuesday. Even if History wasn't there, Economics cannot be on Tuesday. * Tuesday-Wednesday-Thursday: Not possible because History is on Tuesday. * Wednesday-Thursday-Friday: This is the only possible slot for the E-E-M block. 4. Placing the E-E-M block in the only available slot: Wednesday: English Thursday: Economics Friday: Mathematics 5. Now, combine with the fixed History lecture: Tuesday: History Wednesday: English Thursday: Economics Friday: Mathematics 6. The only remaining day is Monday, and the only remaining subject is Statistics. So: Monday: Statistics 7. The final schedule is: Monday: Statistics Tuesday: History Wednesday: English Thursday: Economics Friday: Mathematics Now, answer the question: "Which lecture is scheduled between Statistics and English?" Statistics is on Monday. English is on Wednesday. The lecture scheduled on Tuesday, between Monday and Wednesday, is History. Therefore, History is scheduled between Statistics and English. The final answer is B) History.
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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