Question

question 18 of 22: 7.1 section exercise 47 - 50 (clic) score: 1 / 1 point submitted: sep 15 10:40 pm time spent: 2m 34s use the ti - 84 plus calculator to find the z - scores that bound the middle 94% of the area under the standard normal curve. enter the answers in ascending order and round to two decimal places. the z - scores for the given area are - 1.88 and 1.88.

Explanation:

Step1: Recall the property of the standard - normal curve

The middle area $A = 0.94$. The area in the two tails is $1 - 0.94=0.06$. So the area in each tail is $\frac{0.06}{2}=0.03$.

Step2: Use the inverse - normal function on TI - 84 Plus

On the TI - 84 Plus calculator, we use the invNorm function. For the left - hand $z$ - score, we input invNorm(0.03,0,1) and for the right - hand $z$ - score, we input invNorm(1 - 0.03,0,1).

Step3: Calculate the $z$ - scores

Using the TI - 84 Plus calculator:
The left - hand $z$ - score: invNorm(0.03,0,1) gives approximately $z_1=- 1.88$.
The right - hand $z$ - score: invNorm(0.97,0,1) gives approximately $z_2 = 1.88$.

Answer:

-1.88, 1.88