Example 1

If 36 inches equal 1 yard, 3 yards equal how many inches?

Intuitively, 3 × 36 = 108 in

By proportion, using yards over inches,

Remember: Place the same units across from each other—for example, inches across from inches. Then solve.

Cross multiply.

Example 2

If 2.2 pounds equal 1 kilogram, 10 pounds equal approximately how many kilograms?

Intuitively, 10 ÷ 2.2 ≈ 4.5 kg

By proportion, using kilograms over pounds,

Cross multiply.

Divide and round off to the nearest tenth.

Example 3

Change 3 decades into weeks.

1 decade equals 10 years, so 3 decades equal 30 years.

1 year equals 52 weeks, so

Therefore, there are 1,560 weeks in 3 decades.

Notice that this was converted step by step. It can be done in one step, as follows:

Example 4

If 1,760 yards equal 1 mile, how many yards are in 5 miles?

Therefore, there are 8,800 yards in 5 miles.

Example 5

If 1 kilometer equals 1,000 meters, and 1 dekameter equals 10 meters, how many dekameters are in 3 kilometers?

Since there are 1,000 meters in one kilometer, there will be 3,000 meters in 3 kilometers. Now use a proportion that compares dekameters with meters

Therefore, there are 300 dekameters in 3 kilometers.