FRAME 62.

To find the area for z = 1.67, find 1.67 in the perimeter of the table. The units and tenths

digits (1.6) determine the row and the hundredths digit (.07) determines the column. The value at

the intersection (.4525) is the area under the curve for a distance 1.67 standard deviations above

the mean. The diagram below demonstrates how the area was found:

z

0

1

2

3

4

5

6

7

0.0

*

*

*

*

*

*

*

*

*

*

*

1.6

.4452

.4463

.4474

.4484

*

*

*

.4525

In a similar manner we would find the area under the normal curve from the mean to z = 2.51 to

be .4940. Find 2.51 in the perimeter of the table and, at the intersection of the 2.5 row and .01

column, read the area .4940. If the value of z is negative, it simply means the area is to the left of

the mean. We can ignore the sign and find the area under the curve as before. To preclude

interpolating between two z values, always round to two decimal points. The z value will be

rounded up if it is 5 or greater, or rounded down if it is 4 or less. Indicated below are examples

of rounding the z value.

Original z Value

Rounded

Area

1.2340

1.23

.3907

1.6667

1.67

.4525

2.4934

2.49

.4936

The normal curve table gives areas under the curve for a number of standard deviations (z's)

measured from the mean.

FRAME 63.

Find the areas under the curve associated with the following values for z:

a. 1.34

b. 2.69

c. 1.00

d. 3.00

e. -.09

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