# S1 Edexcel question help please!Watch

Thread starter 7 years ago
#1
I'd really appreciate it if you could look at this paper please
http://www.edexcel.com/migrationdocu...e_20090119.pdf

A quick question with question 3e,

0.3x0.1 + 0.1x0.3 + 0.2x0.1 + 0.1x0.2 + 0.1x0.1 + 0.2x0.2 = 0.15

However, why isn't the (0.2x0.2) and (0.1x0.1) done twice like the others?

Hope that makes sense

Would really appreciate the help

thank you!!
0
7 years ago
#2
Getting 3 and 3, and 2 and 2 can only be achieved one way. The others can be achieved two ways, so the probability is doubled: for example, to get 1 and 3, you could first get 1, then get 3; or get 3, then get 1.

I hope that makes sense!
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