You are Here: Home >< Maths

# S1 nCr problem watch

1. Hi guys, needing some help with some nCr, nPr and factorial S1 stuff here;

At a small branch of the Mid-West Bank, the manager has a staff of 12, consisting of 5 men and 7 women including a Mr Brown and Mrs Green. The manager receives a letter from Head Office saying that 4 of his staff are to be made redundant. In the interests of fairness the manager decides to select the 4 staff at random.
(i) How many different selections are possible?
(ii) How many of these selections include both Mr Brown and Mrs Green?
(iii) Write down the probability that both Mr Brown and Mrs Green will be made redundant.

I can do part i but part ii I have no idea how to do.

Thanks
2. Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.
3. (Original post by Chonty)
Hi guys, needing some help with some nCr, nPr and factorial S1 stuff here;

At a small branch of the Mid-West Bank, the manager has a staff of 12, consisting of 5 men and 7 women including a Mr Brown and Mrs Green. The manager receives a letter from Head Office saying that 4 of his staff are to be made redundant. In the interests of fairness the manager decides to select the 4 staff at random.
(i) How many different selections are possible?
(ii) How many of these selections include both Mr Brown and Mrs Green?
(iii) Write down the probability that both Mr Brown and Mrs Green will be made redundant.

I can do part i but part ii I have no idea how to do.

Thanks
for ii) you have removed Mr B & Mrs G from the list. you now have to choose 2 people from the remaining 10.
4. (Original post by the bear)
for ii) you have removed Mr B & Mrs G from the list. you now have to choose 2 people from the remaining 10.
Thanks

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: November 7, 2017
Today on TSR

### Edexcel GCSE Maths Unofficial Markscheme

Find out how you've done here

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams