# A level Maths (Stats) help

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Hi, i was wondering if anyone could show me how to do these questions. I have the answers in the back of the book but i dont know how they were achieved.

1. A shop stocks tinned cat food of two makes A and B, and two sizes, Large and Small. Of the stock 70% is brand A 30% is brand B. Of the tins of brand A 30% are small sized, of brand B 40% are small sized. Find the probability that: a) a tin chosen at random is a small one b) a small tin chosen at random will be of brand A.

2. A boy either walks to school or goes by bus. If one day he goes to school by bus then the probability he goes by bus the next day is 7/10. If one day he walks to school, then the probability that he goes by bus the next day is 2/5. a) Given that he walks to school on a particular tuesday, find the probability that he will go to school by bus on Thursday. b) Given that he walks on both Tuesday and Thursday find the probability that he will also walk on Wednesday.

3. For married couples the probability that the husband has passed his driving test is 7/10 and the probability the wife has is 1/2. The probability that the husband has passed given the wife has passed is 14/15. Find the probability that, for a randomly chosen couple, the driving test will have been passed by:a) both of them b) one of the, c) neither of them
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