GATE 2011 CS (CS1) – Question 44

Engineering Mathematics · Probability and Statistics · 2 marks · Multiple choice

Five cards numbered one through five are shuffled. Draw two without replacement. What is the probability the first card’s number is exactly one higher than the second’s?

$1/5$
$4/25$
$1/4$
$2/5$

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Correct answer: (A) $1/5$

Explanation

There are 5×4=20 equally likely ordered draws. Favourable pairs are (2,1),(3,2),(4,3),(5,4), four outcomes. Thus probability is 4/20=1/5, A. “One higher” means difference exactly one, not merely greater.

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