some probability questions.. (1 Viewer)

[oranGez]

hey guys, i am absolutely fc*ked for probability .. im only up to ordered and unordered selections and already im stuck.. the following questions are the ones i just cannot get the answer for and i have no idea why.. theyre probably really easy, sorry ..

1. A poker machine has 4 wheels and each wheel can show 10, J, K, Q or A. How many outcomes are possible?
A = 625

2. The letters of the word MATHS are randomly arranged. Calculate the probability that the arrangement begins with M and ends with S.
A = 1/20

3. In poker, a 'royal flush' is getting 10, J, Q, K and A of the same suit. Show that there is 1 chance in 649740 of achieving this.

4. A bag contains 10 $2 coins, 5 $1 coins and 15 10c coins. Melanie randomnly selects 3 coins from the bag. What is the probability that she brings out 2 10c coins?
A = 45/116


I have a lot more questions but i guess that's a start. As you can see i really have no idea how to work out probabilities for specific things within the selection...if that makes sense..like, say there were 6 red marbles and 4 blue marbles..i have no idea how id work out the probability of choosing 3 red and 1 blue..

thanks for your help

 

[withoutaface]

1. 5^4
2. 3!/5!
3. 5/13*4/51*3/50*2/49*1/48

 

[FinalFantasy]

1. 5^4
2. 3!/5!
3. 5/13*4/51*3/50*2/49*1/48

general maths learns factorial notations?

 

[shafqat]

theres a 5/13 chance of chosing 10,J,Q,K,A of any suit, and then u have to chose the other four cards in the suit u have chosen

 

[oranGez]

oh shat, im such an idiot, i thought for the poker machine was u could get each suit as well.. but for the letters of MATHS.. how come its 3! divided by 5! ?? i mean, i know its the right answer and everything (and i thank u muchly for doing it too lol) but why do u do it that way? sorry if im a bit dense.. so much for selective school people being smart

 

[shafqat]

oh shat, im such an idiot, i thought for the poker machine was u could get each suit as well.. but for the letters of MATHS.. how come its 3! divided by 5! ?? i mean, i know its the right answer and everything (and i thank u muchly for doing it too lol) but why do u do it that way? sorry if im a bit dense.. so much for selective school people being smart

the letters of maths can be ordered in 5*4*3*2*1 ways. do it like this: have boxes. there are five possible letters to fill the first box, four for the next....

if m is the first, s last, then there are 3 spaces to fill: 3*2*1

hence 3!/5!

hope that was explained ok :S

 

[oranGez]

hey! i get it! thats so simple.. im kicking myself right now for not knowing how to do it... gargh, thanks a lot guys! you've saved me hours of anguish i can tell who'll be getting top marks in their hsc...

//EDIT__ oops, looks like some of you have already finished your hsc haha

 

[PC]

Answers to Probability Questions

Hey Orangez!

Here are my full answers, hope this helps. See attachment.