Question

A box contains 10 black and 10 white balls. The probability of drawing two balls of the same colour, is: 919 938 1019 519

Answer 1

# Answer =1/2

# Explaination-

We have two states for the first ball,

either you pick a white ball 1/2 of the time or black ball 1/2 of the time.

If you pick a white ball you have a 1/2 chance of picking another white ball for a probability of 1/4 to pick two white balls.
If you pick the black ball you have a 1/2 chance of picking another black ball for a probability of 1/4 to pick two black balls.

The sum of the two is 1/2 to chose two identically colored balls of either color.

Probability (x)= (1/2)^2+(1/2)^2

Probability (x)= 1/2.

Probability of drawing two balls of same colour is 1/2.

Hope this helps...