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# S2 OCR textbook solutions Watch

1. Was wondering if there was anywhere anyone new of with solutions to the OCR S2 textbook by Steve Dobbs and Jane Miller? Or if not, the particular question I could do with help on is question 6 in exercise 4A:
"An unbiased dice is thrown once. Write down the probability distribution of the score X and show that Var(X) = 35/12.
The same dice is thrown 70 times.
(a) Find the probability that the mean score is less than 3.3.
(b) Find the probability that the mean score exceeds 3.8."
Thanks
2. The answers in the back are (a) 0.155 and (b) 0.0662, but I don't know how to get to them!

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Updated: March 31, 2013
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