Question

I was wondering how to find the are left of a z score on a TI-84 calculator.

For example, find the area to the left of z=-3.20 when the mean is 64.2 and standard deviation is 4.2

Please explain with the use of the TI 84!

Answer 1

Area to the left of Z = - 3.20 is identical to cumulative area under standard normal distribution = 0.00068714

The above value is got with the use of the TI 84 calculator as follows:

Since Z = - 3.20 is directly given, = 0 and = 1.

The syntax of the format of the function to use is as follows:

normalcdf(lower bound, upper bound, mean, standard deviation)

Inthis problem, area to the left of Z = - 3.20 is to be calculated>

So,

lower bound is - . The smallest value the calculator can handle is - 1 X 10⁹⁹. This is typed in calculator as - 1 E 99.

upper bound - 3.20

mean = 0

standard deviation = 1

So,

the function to use is:

normalcdf(-1E99, -3.20,0,1).

The result is:

0.00068714