The probability of drawing two white cards without replacement is 1495 , and the probability of drawing one white card is 25 . what is the probability of drawing a second white card, given that the first card is white?

Note: Probabilities are 14/95 and 2/5.

Solution:
If P(w1) and P(w2) are the probabilities of drawing two white cards without replacement, then
P(w1)*P(w2) = 14/95 and P(w1) = 2/5

Therefore,
P(w2) = (14/95)/P(w1) = (14/95)/(2/5) = 14/95 * 5/2 = 7/19

Then, probability of drawing a second white card given the first one is white is 7/19.

7/19 is correct. I just took the test.

Step-by-step explanation:

2.4 hours.

Step-by-step explanation:

Remark

The supervisor is not quite correct. The correct answer must be lower than the lowest number, otherwise you are taking out what the person with the narrower hose must be taking out what the other person is putting in.

Equation

Let x = the amount of time needed for him to fill the pool

Let y = the amount of time needed for the second person to fill the pool

Let z = the amount of time needed for both to fill the pool.

1/x + 1/ y = 1/z

1/4 + 1/6 = 1/z         The common denominator is 12

3/12 + 2/12 = 1/z

5/12 = 1/z                Cross multiply

5z = 12 * 1               Divide by 5

z = 12/5

z = 2 2/5

z = 2.4 hours