June Answer:

Problem: The world record for the women's 100-meter dash is 10.49 seconds. How fast is that in kilometers per hour?

Solution:

Record = 100m/10.49 sec.
Setting up proportions in order to convert, allows students to eliminate units:see equation:

     100m/10.49 sec  60sec/1min   60min/1 hr  1km/1,000m

Cancel units then multiply: 100x60x60x1 km     =  360000km  or 34.23 km/hr
                                                    10.49x1x1x1,000 hr    10,490 hr