Question

If you randomly pick a number from 1 to 25, what is the probability that the number will have “2” as one of the digits?

Answer 1

7/25 because that is the about of numbers that have a two in it

Answer 2

`(7)/(25)`

Explanation:

In the interval
`n\in [1, 25]`, there are
`(25-1)+1=25` numbers total. The number
`2` appears as the ones digit for
`3` numbers in this interval:
`0\bold{2}, 1\bold{2}, 2\bold{2}`. The subset
`n\in [20, 25]` marks the interval of numbers in the set that has the number
`2` as the tens digit. There are
`(5-1)+1=5` numbers in this set. Since
`22` is counted twice, there are a total of
`5+3-1=7` numbers in the original interval that contain the number
`2`. Therefore, the probability a random selected number from the interval has the number
`2` in it is
`\fbox{$(7)/(25)$}`.