I was recently at a statistics competition and a question came up as follows:
They drew a normal distribution with $\mu=7$ and the area between the values $7.75$ and $8.25$ equal to $0.12$. No other information was provided.
In order to solve the rest of the question you had to figure out the standard deviation. In the solutions guide they said 'Well if you look at it its probably $\sigma=1.1$' Evidently, if you do
pnorm(7.75,8.25,7,1.1) you get 0.1179... which is definitely not 0.12.
I later solved this question using wolfram alpha and the integral form of the normal CDF function (and got $\sigma=0.904...$), but figured there has to be a better way.
NOTE: This will be used on a TI-NSpire CAS