Video Solutions to help Grade 6 students learn how to solve constant rate work problems by calculating and comparing unit rates.
• Students solve constant rate work problems by calculating and comparing unit rates.
• Constant rate problems always count or measure something happening per unit of time. The time is
always in the denominator.
• Sometimes the units of time in the denominators of two rates are not the same. One must be converted to the other before calculating the unit rate of each.
• Dividing the numerator by the denominator calculates the unit rate; this number stays in the numerator. The number in the denominator of the equivalent fraction is always 1.
Example 1: Fresh-Cut Grass
Suppose that on a Saturday morning you can cut 3 lawns in 5 hours, and your friend can cut 5 lawns in 8 hours. Your friend claims he is working faster than you. Who is cutting lawns at a faster rate? How do you find out?
Example 2: Restaurant Advertising
Next, suppose you own a restaurant. You want to do some advertising, so you hire 2 middle school students to deliver take-out menus around town. One of them, Darla, delivers 350 menus in 2 hours, and another employee, Drew, delivers 510 menus in 3 hours. You promise a $10 bonus to the fastest worker since time is money in the restaurant business. Who gets the bonus?
Example 3: Survival of the Fittest
Which runs faster: a cheetah that can run 60 feet in 4 seconds or gazelle that can run 100 feet in 8 seconds?
Example 4: Flying Fingers
What if the units of time are not the same in the two rates? The secretary in the main office can type 225 words in 3 minutes, while the computer teacher can type 105 words in 90 seconds. Who types at a faster rate?