1.

Two balls are drawn at random from a bag containing 2 white, 3 red, 5 green and 4 black balls, one by one without, replacement. Find the probability that both the balls are of different colours.

Answer»

given: 2 white, 3 red, 5 green, 4 black

Formula: P(E) = \(\frac{favorable\ outcomes}{total\ possible\ outcomes}\) 

two balls are drawn one by one, we have to find the probability that they are of different colours

total possible outcomes are 14C2 

therefore n(S)= 14C2 = 91

 let E be the event that all balls are of same colour 

E= {WW, RR, GG, BB} 

n(E)= 2C23C25C24C2 = 20 

probability of occurrence is

P(E) = \(\frac{n(E)}{n(S)}\)

P(E) = \(\frac{20}{91}\) 

Therefore, the probability of non-occurrence of the event (all balls are different) is

P(E') = 1- P(E) 

P(E') = \(1-\frac{20}{91}=\frac{71}{91}\) 



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