# A bag contains 4 blue and 5 green balls. Another bag contains 3 blue and 7 green balls. If one ball is drawn from each bag, what is the probability that two balls are of the same colour? - Mathematics and Statistics

Sum

A bag contains 4 blue and 5 green balls. Another bag contains 3 blue and 7 green balls. If one ball is drawn from each bag, what is the probability that two balls are of the same colour?

#### Solution

Let A be the event that a blue ball is drawn from each bag.
Probability of drawing one blue ball out of 4 blue balls where there are a total of 9 balls in the first bag and that of drawing one blue ball out of 3 blue balls where there are a total of 10 balls in the second bag is

P(A) = 4/9xx3/10
Let B be the event that a green ball is drawn from each bag.
Probability of drawing one green ball out of 5 green balls where there are a total of 9 balls in the first bag and that of drawing one green ball out of 7 green balls where there are a total of 10 balls in the second bag is

P(B) = 5/9xx7/10

Since both, the events are mutually exclusive and exhaustive events
∴ P(that both the balls are of the same colour)
= P(both are of blue colour) or P(both are of green colour)
= P(A) + P(B)
= 4/9xx3/10+5/9xx7/10

= 12/90+35/90

= 47/90

Is there an error in this question or solution?
Chapter 7: Probability - Exercise 7.4 [Page 108]

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