Project ForgeEngineering Mathematics
Calculus
GATE 2018
Medium
Four red balls, four green balls and four blue balls are put in a box. Three balls are pulled out of the box at random one after another without replacement. The probability that all the three balls are red is
- A1/72
- 1/55
- C1/36
- D1/27
Explanation
Drawing without replacement: P(all three red) = (4/12)×(3/11)×(2/10) = 24/1320 = 1/55.
Source: GATE ME 2018 Session 1 (Set 1) (2018)
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