Letters and packages can take up to 2 days to be delivered by Speedipost couriers. The following table shows the percentage of items delivered at certain times after sending.

a. Is there any truth in the statement ‘If you post 10 letters on Monday then only nine of them will be delivered before Wednesday’? Give a reason for your answer.

b. Find the probability that when three letters are posted on Monday, none of them are delivered on Tuesday.

c. Find the probability that when a letter and a package are posted together, the letter arrives at least 1 day before the package.

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Same day After I day fter 2 days Letter 40% 50% 10% Package 15% 55% 30%