Using scientific notation, it is found that the measure of one astronomical unit in kilometers is 
A number in <em>scientific notation</em> is given by:

- In which

- To realize the conversion from decimal to scientific notation, b is the number of decimal places the comma moves, being positive if to the left, negative if to the right.
In this problem, 1 AU = 150,000,000 km.
- The comma has to move 8 places to the right, hence

Then, the measure is: 
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We are given the fact that he plays football, so the probability of his being a football player is 100%.
We know that 1/3 of the football players also play baseball, so the probability that he is also a baseball player is 1/3.