How did ye do maths p2 Q6-c

emma.oshea

hey guys can any1 tell me how you did this question...and how sure you are that u were right!
thanks a mil

Raphael

Higher, yeah? I'll do it out for you as I did it

emma.oshea

ya higher!
thanks

Raphael

No problem, I have a day off today and I'm bored.

Need me to explain any parts of it?

emma.oshea

that was quick, thanks very much, u made it look so easy.
im trying to do 7(aii) just trying to figure out if its right.

Raphael

Want me to do that out for you as well?

And it's only easy because i figured it out in the exam, wasn't easy the first time

emma.oshea

Please ya i just cant get my head around it...i know what its asking but i just cant figure the damn thing out! yo uknow for 61 why do u have the 30/30? and then all 1/30

Raphael

Because it's asking you to find the probability they're all on the same date, right? So when you look at each student you have to work out the probability that they have the same date as the person before them.

In the case of the first person, there's no one before him, so any date is the same as the guy before him. There's a probability of 1 that his birthday won't be different from anyone we've looked at so far

After that though, all the birthdays have to be the same date. Hence the 1/30's

Say, for instance, the first guys birthday was june 8th. then all the rest of them ahve to be june 8th as well. But if his had been June 16th, they'd all have to be june 16th.

Am I making sense?

emma.oshea

Cheere that makes perfect sence. For 7ai, why is it 10 and not 9? becasue there are only a possibility of 1-9 coming up?

emma.oshea

oops just realised that 0 could also appear....

Raphael

emma.oshea wrote:

oops just realised that 0 could also appear....

Yup, that's why.

emma.oshea

thanks so much... i dont think i did very well but hey what can i do now!

Raphael

You never know, I'd say it's going to be marked fairly easily this year.

Glazun

You could form a terrorist organisation and kidnap the maths paper 2 answer books. Thats if you really wanted to. Though forming terrorist organisations is frowned upon..