i am noob at probability! XD

davidche SG

In a game, 2 dices are thrown together. Die A has 2 red faces and 4 blue. Die B has 4 red and 2 white faces. Find the probability that there is at least one red face on top.

Could you guys do the working out? btw i wasnt tot the textbook way. XD

deteq SG

P(at least one red face)= (2/6 * 4/6) + (2/6 * 2/6) + (4/6 * 4/6)

= 7/9

correct or not ah.

kenn3th SG

correct.

alternatively you can find the other one without any red.

so it's 4/6 x2/6 = 2/9

1 -2/9

Ferrari_RoXz SG

P(at least one red face)= (2/6 * 4/6) + (2/6 * 2/6) + (4/6 * 4/6)

= 7/9

correct or not ah.

Ya, shld be correct. I got the same answer as you.

deteq SG

yay! tomorrow no fear

davidche SG

hehe correct. same as ans key

iamapebble SG

I got question I got question!

If they ask such questions like at least one red or something even though you have like R,B, you also have to include B,R. Is there any case where you won't have to? Is it when you replace the thing uh? Scared tomorrow suddenly cannot do. ^^"

Garrick_3658 SG

Draw tree diagram bah.

charlize SG

All you need is to pick up gambling and your probability skills will improve.

Try Blackjack, Big-small, Roulette, Caribbean Stud Poker, Craps etc

eagle SG

More probability questions here... although still not a lot yet :(

http://examworld.blogspot.com/search/label/O%20lvl%20EM%3A%20Probability

davidche SG

denominater minus one right>?

I know i suck in probability but even when u times 2 to P when you are looking for Either One, it is essentially P+ P

So when there is no replacement, you just -1 from the denominater and do the same P + P(denom - 1) lo.

davidche SG

gosh i am still havin problems with probability. I will not go to sleep unless i have this cleared in my mind.

davidche SG

P(at least one red face)= (2/6 * 4/6) + (2/6 * 2/6) + (4/6 * 4/6)

= 7/9

why is it (4/6 * 4/6)

shldnt it be 4/6 *1 + 2/6 *1?

Creeed SG

4/6 * 4/6 is when die A shows a blue face and when die B shows a red face. think of all the possibilities where you have at least 1 red.

Both red. die A red only or die B red only.