Question

Find the value of the standardized z-test statistic and the area above 140 for a N(160,25) distribution. Round your answer to three decimal places.A) z = - 0.8, area = 0.212B) z = -0.8, area = 0.788 C) z = 0.8, area = 0.212 D) z = 0.8, area = 0.788

Answer 1

B

Explanation:

standard z-test statistic=x-mean/standard deviation

N(160,25)⇒N(mean,standard deviation)

mean=160

standard deviation=25

x=140

z=140-160/25=-20/25=-0.8

area above 140=P(z>0.8)=P(-0.8<z<0)+P(0<z<∞)=0.2881+0.5=0.7881

so z=-0.8, area=0.7881