Question

1. On the standard normal curve, find the following values of z. a. the value of z representing the 75th percentile or upper quartile b. the value of z representing the 15th percentile C, the value of z that cuts of the upper 25% of the area under the curve 2. Find the area under the standard normal curve to the left of 1.2 3. Find the area under the standard normal curve to the right of 2.48. 4. Find the area under the standard normal curve between -1.30 and 1.75.

Answer 1

Solution(1a)

Given in the question

P-value =0.75

From Z table we found z value

So z value = 0.675

Solution(1b)

P-value =0.15

So from z table we found z value

Zvalue = -1.04

Solution(1c)

P-value =0.75

And z value is 0.675

Solution(2)

Z =1.21

This is left tailed test so p-value from z table is

P(Z<=1.21)= 0.8869

Solution(3)

Z =2.48

And this is right tailed test

So P(Z>2.48)= 0.0066

Solution(4)

P(-1.30<Z<1.75) = P(Z<1.75)-P(Z<-1.30)

= 0.9599- 0.0968 = 0.8631