1 In a standard Normal model what values of x cuts off the r

1) In a standard Normal model, what value(s) of x cut(s) off the region described? a) the lowest 12% b) the highest 30% c) the highest 7% d) the middle 50%

Solution

(a)

From z-table , z-score -1.175 has area 0.12 to its left. So required cutoff is -1.175.

(b)

Highest 30% means, lowest 70%. From z-table, z-score 0.524 has area 0.70 to its left. So required cutoff is 0.524.

(c)

Highest 7% means, lowest 93%. From z-table, z-score 1.476 has area 0.93 to its left. So required cutoff is 1.476.

(d)

The middle 50% means, area to left of middle 50% is 0.25 and area to the right of middle 50% is 0.25. From z-table, area left to z-score -0.674 is 0.25 and area right to z-score 0.674 is 0.25. So area between -0.674 and 0.674 is 0.50.