A box contains 5 green, 4 yellow and 5 white pearls. Four pearls are drawn at random. What is the probability that they are not of the same colour ? A) 11/91 B) 4/11 C) 1/11 D) 90/91
A box contains 5 green, 4 yellow and 5 white pearls. Four pearls are drawn at random. What is the probability that they are not of the same colour ? A) 11/91 B) 4/11 C) 1/11 D) 90/91 Correct Answer Option D
Let S be the sample space. Then,n(s) = number of ways of drawing 4 pearls out of 14
= C414 ways = 14×13×12×114×3×2×1= 1001
Let E be the event of drawing 4 pearls of the same colour.Then, E = event of drawing (4 pearls out of 5) or (4 pearls out of 4) or (4 pearls out of 5)
⇒C15+ C44+ C15 = 5+1+5 =11
P(E) = n(E)n(S)=111001=191
Required probability = 1-191=9091
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Feb 20, 2025