Question

About _______% of the area under the curve of the standard normal distribution is outside the interval z=[−2.23,2.23] (or beyond 2.23 standard deviations of the mean).

please explain how to solve using ti84

Answer 1

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P(z > 2.23 or z<-2.23)

= 1- P(-2.23<Z<2.23)

= 1- (0.987126279 - 0.012873721)

= 1- 0.9743

= .0257

To do the same in ti84, follow these steps:

Two Tailed (non-directional) z-test:

1) Calculate z_calc (z_test)

2) Find the absolute value of z_calc ( in our case 2.23 and -2.23)

3) 2nd DISTR

4) Scroll down to normalcdf()

5) ENTER

6) Now enter: |z_calc|, 1000, 0,1)

7) ENTER

8) Output is ½ of the P-value

9) So, Multiply result by 2

10) subtract this value from 1 to get your answer.