The Student Room Group

Number of possibilities

To families are chosen at random. Each family has one male and one female.

Given that only one male out of both families and one female from both families have jobs, find the number of different arrangements for those with jobs.


-------
OK

So the arrangement is

(HW') (H'W)
OR
(H'W) (HW')
OR
(H'W') (HW)
OR
(HW) (H'W')

so there are four options

Is there a better way to work this out other than trial and error?
The fact that they are in families is, in effect, irrelevant to the question.

There are 2 males and 2 females. One from each works, hence:

2C1×2C1^2C_1\times ^2C_1
can you please explain whY???
Original post by jsmith6131
can you please explain whY???


Which bit?
why it is 2C1 * 2C1
Reply 5
Original post by jsmith6131
why it is 2C1 * 2C1


these are the different way in which you can pick 1 from 2, since there are 2 couples, you multiply one by the other. You have 4 different combinations. 1
(edited 12 years ago)
There are 2 males, of which one is working, so 2C1, choose 1 from 2.

Similarly females, and multiply.
Reply 7
Maybe you can think about it in terms of 2!*2! .
Use binomial distribution > if you didn't understand the above post then you should revise binomial, this is simply based on basic binomial.
(edited 12 years ago)
Reply 9
By the looks of the question he is using s1.
ye its S1 but I have studied basic binomial

ghost water explained it sufficuently so thanks guys

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