# Homework

Watch
Announcements
#1
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
0
#2
0
2 years ago
#3
(Original post by Masonboss19)
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
Construct a probability tree.

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).
0
2 years ago
#4
You’ll have to draw a tree diagram and work it out
Last edited by _unknown167; 2 years ago
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Poll: What factors affect your mental health most right now? Post-lockdown edition

5.81%
Uncertainty around my education (77)
11.77%
Uncertainty around my future career prospects (72)
11.01%
Lack of purpose or motivation (83)
12.69%
Lack of support system (eg. teachers, counsellors, delays in care) (37)
5.66%
Impact lockdown had on physical health (37)
5.66%
Social worries (incl. loneliness/making friends) (70)
10.7%
Financial worries (41)
6.27%
Concern about myself or my loves ones getting/having been ill (26)
3.98%
Exposure to negative news/social media (39)
5.96%
Difficulty accessing real life entertainment (19)
2.91%
Lack of confidence in making big life decisions (63)
9.63%
Worry about missed opportunities during the pandemic (52)
7.95%