Question

Find the z value that satisties each of the following conditions(report the value of z that comes closest to satisfying the condition). In each case, sketcha standard Normal curve with your value of z marked on the axis. 7. 20% of the observations fall below z. (Sketch the graph and shade the given area) (20% = 0.20)That is, find the z value corresponding an area of 0.20 on the left of it. a) 30% of the observations fall above z. (Sketch the graph and shade the given area). (0.30 = 30%) That is, find the z value corresponding to an area of 0.30 to the right of it b)

Answer 1

a) P(Z < a) = 0.20

Z score at p = 0.20 using excel = NORM.S.INV(0.20) = -0.84

-0.84 一. . -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 2.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

b) P(Z > a) = 0.30

= 1 - P(z < a) = 0.30

= P(z < a) = 0.70

Z score at p = 0.70 using excel = NORM.S.INV(0.70) = 0.52

0.52 -0.1 -3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5