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GATE 2021 MT – Question 7

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 2 marks · Multiple choice

A box contains 15 blue and 45 black balls. Two are selected randomly without replacement. The probability that the first is blue and the second black is ______.

  1. $3/16$
  2. $45/236$
  3. $1/4$
  4. $3/4$

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Show answer and explanation

Correct answer: (B) $45/236$

Explanation

Without replacement, probability is (15/60)(45/59)=45/236. The second denominator decreases by one while black-ball count stays 45.

Thus **45/236, B**.