Answer to Question #248561 in Statistics and Probability for james

Question

In Statistics and Probability 50-item test of Grade 11 ABM E the mean of their scores is 37 and a standard deviation of 8.

       a. Find the lowest score of the upper 20% of the distribution (80^th Percentile)

       b. What is the highest score of the 35^th Percentile (lower 35% of the distribution)?

Answer 1

a.

$P=0.8$

$z=0.845$

$z=\frac{x-\mu}{\sigma}$

$x=z\sigma +\mu=0.845\cdot 8+37=43.76$

lowest score of the upper 20% of the distribution = $44$

b.

$P=0.35$

$z=-0.385$

$x=-0.385\cdot 8+37=33.92$

the highest score of the 35^th Percentile = 34.