The Obama vacations have cost an average of 4 million and a standard deviation of 5 million. The Bush vacations have cost an average of 3 million and a standard deviation of 2 million. What is more unusual: an Obama vacation that costs 5 million or a Bush vacation that cost 1 million?
What I think: I don't know what "more unusual" means in statistics. I tried to solve this problem by comparing the standard deviation and the z-interval.
Bush's vacation costing $1,000,000 is a $1,000,000 less than average, for Bush: a full standard deviation lower than average. Obama's vacation costing $5,000,000 is only 1/5 th of a standard deviation higher than average.
So Bush's vacation cost deviated more from the average, with respect to for Bush, than did Obama's (with respect to Obama's average costs), i.e., Bush's vacation cost was the more unusual in the sense that his vacation costs deviated more than is typical for Bush, than did Obama's vacation cost from what is typical for Obama.