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# S1 help please :) watch

1. Hi I've got an S1 mock exam tomorrow and am stuck on 1 of the past papers

The question says, "When carrying X passenger, the charge per mile is £Y where Y = 1/4 (x+2). What is the mean and variance of Y?"

I've worked out E[X], which is 2.05 and I (sort of) know how to work out the mean and variance of Y, but the fraction before (x+2) is confusing me

For the mean, do I work out E[Y] = E[X] +2 and then divide the answer by 4, or maybe 4E[Y] = E[X] + 2 and then find Y, or I am totally wrong? Is there a 'proper' method I should use?

Thank you
2. Bump

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