Ahh i realised my error. Part ii is simply 5/6 cubed, which is the probabilty of not obtaining a six when a dice is thrown. Would you like workings fr the other 2 parts?

Reply 14

mupsman2312

Original post by Asad234

For part (i), think about the probability of getting all three sixes, and then the probabilities of each of the three ways of getting exactly two sixes; add the results together.

For part (ii), find the probability of not getting a six with one of the dice, and then cube it.

For part (iii), I would try to think of all combinations of how you can get at least two numbers the same, and their probabilities together, and then subtract this value from 1.

I hope that this helps! :smile:

EDIT: Actually, my method for part (iii) is overly long-winded. beckyyfoster did a much better solution three posts down.

Spoiler

(edited 6 years ago)

Reply 15

Asad234

Original post by Radioactivedecay

Ahh i realised my error. Part ii is simply 5/6 cubed, which is the probabilty of not obtaining a six when a dice is thrown. Would you like workings fr the other 2 parts?

yes, please.

Show me all the working for all the parts please. thank you

Reply 16

Asad234

Original post by thekidwhogames

Part ii:

P(6' :wink:

= 1-P(6) = 5/6.
Hence 5/6 cubed = 125/216 (as three rolls).

thx

Reply 17

beckyyfoster

okay so:

ii) probability of no 6's means throwing a 1/2/3/4/5 on all 3 throws
therefore: 5/6 * 5/6 * 5/6 = (5/6)^3 = 125/216

iii) different scores on all dice mean throwing any on 1st throw, so then there are only 5 possibilities for 2nd and 4 for third
therefore: 1 * 5/6 * 4/6 = 20/36 = 5/9

Reply 18

Radioactivedecay

Original post by Asad234

yes, please.

Show me all the working for all the parts please. thank you

Part i) it is simply the probability of getting two sixes, which can happen 3 different ways plus the probability of getting 3 sixes because it says at least two sixes meaning 2 or greater. So you get 3x (1/6 x1/6 x5/6) + (1/6)^3.
Part iii is simply 1/6 x 5/6 ( because you have 5 remaining digits to choose from) x4/6 ( because you have 4 remaining digits to choose from). This can happen 6 different ways so we multiply by 6.