An urn contains 5 red balls and 2 green balls. Two balls are drawn one after the other. What is the probability that the second ball is red?

The probability that the second ball is red is 71%

Step-by-step explanation:

Probabilities

We know there are 5 red balls and 2 green balls. Let's analyze what can happen when two balls are drawn in sequence (no reposition).

The first ball can be red (R) or green (G). The probability that it's red is computed by

The probability is's green is computed by

If we have drawn a red ball, there are only 4 of them out of 6 in the urn, so the probability to draw a second red ball is

If we have drawn a green ball, there are still 5 red balls out of 6 in the urn, so the probability to draw a red ball now is

The total probability of the second ball being red is

The probability that the second ball is red is 71%

it would take 7/10 of an hour too fill the pool.

step-by-step explanation: