Question

A bag contains 10 counters. 6 of them are white. a counter is taken at random and not replaced. A second counter is taken out of the bag at random. Calculate the probability that only one of the two counters are white

Answer 1

Answer:

$\frac{8}{15}$

Step-by-step explanation:

The ways we can get "1 counter to be white out of 2 draws" is:

1. If 1st one taken out is white and next one different color, and

2. If 2nd one taken out is white and 1st one different color

In probability, AND means MULTIPLY and OR means ADD

Here, we are actually looking for ways of 1st one white, next one different OR first one different and next one white. Let's find them separately.

1. If 1st one taken out is white and next one different color

there are 6 white and 10 total, so 1st one white is 6/10

not replaced, so now there are 9 total and 4 of them are different,so different probabililty is 4/9

We multiply these two to get:  6/10 * 4/9 = 4/15

2. If 2nd one taken out is white and 1st one different color

probabilty 1st one different color is 4/10 since 4 are different and we have total of 10

since not replaced, now we have 9 total and still 6 white.

probability of white in 2nd draw is 6/9

We multiply these two to get:  4/10 * 6/9 = 4/15

Now we add these 2 as stated earlier, so 4/15 + 4/ 15 = 8/15