Answer
No, it would not be unusual to observe 185 smokers who started smoking before the age of 21. This is because 185 is less than 2 standard deviations away from the mean.
Work Step by Step
If the observation is at least 2 standard deviations away from the mean (less than μ−2σ or greater than μ+2σ) then it is considered unusual.
μ−2σ = 180 - 2(4.243) = 171.514
μ+2σ = 180 + 2(4.243) = 188.486
Since 185 falls between 171.514 and 188.486 it is not an unusual value.
