If a bag has 10 counters and 6 of them are white then a counter is taken out of the bag and NOT replaced and a second is taken out at random calculate the probability that only 1 of the 2 counters are white
If you know that 6 of the counters are white then the probability of getting a white the first time is 6/10.
So the probability of not getting a white is 4/10.
The counter taken out is not replaced so you only have 9 counters left in the bag.
Therefore if you chose a white counter the first time, the probability of choosing a white counter the second is 5/9 (1 less white counter, 1 less counter in total). Use this to calculate the probabilities on the second pick.
Then once you have all the probabilities, add up the probabilities of the scenarios where a white counter is only picked once (e.g white counter the first time and not white the second).