Figure 4.3-14 Ratio 1

where to place the decimal point. The DISTANCE and TIME scales are identical and

designed in such a manner that when a ratio or fraction is set up on the scales, all other

possible fractions of equal value are automatically set up. Distance will be placed, or read,

on the DISTANCE (outer) scale, and time will likewise be placed, or read, on the TIME

(inner) scale. Setting them up on the DISTANCE and TIME scales exactly as they would be

written on a piece of paper solves ratios.

There are some important rules to remember when setting up ratio problems on the whiz

wheel:

Units of measure in the numerators must be the same (i.e. nm or pounds).

Units of measure in the denominators must be the same (i.e. minutes or seconds).

The units are placed on the whiz wheel with numerator values on the outside and

denominator values on the inner wheel. (Figure 4.3-14)

Figure 4.3-14 Ratio 1

EXAMPLE: In the following ratio, solve the unknown factor (X):

1=8

2 X

Solution:

The unknown, X, can be found by transferring the ratio directly to the outer

and inner scales as described below.

First, estimate the answer: Since 8 is about eight times 1, then "X" is about eight

times larger than 2 or about 16.

4.6-61