(1) 1E99 is engineering notation for `1"x"10^99` , or effectively infinity. Your calculator is finding the area under the standard normal curve between two values. It uses a numerical approximation technique, and is unable to handle infinity as an input. However, it can handle an absurdly large number like `10^99` .

(2) In a TI-83/84 normalcdf(99,1E99,87,11.4704) gives the area under the standard normal curve from 99 to infinity* if the mean is 87 and the standard deviation is 11.4704.

Alternatively, you could convert all the numbers to standard z-scores. If `x=99,mu=87,sigma=11.4704` then `z=(99-87)/(11.4704)~~1.0462`

Then P(x>99)=P(z>1.0462) and the latter can be found by using normalcdf(1.0462,1E99) as this assumes a mean of 0 and a standard deviation of 1.

Hope this helps.