Hippos Love Pumpkins

Task

1. Hippos sometimes get to eat pumpkins as a special treat.

   

   If 3 hippos eat 5 pumpkins, how many pumpkins per hippo is that?

2. Lindy made 24 jelly-bread sandwiches with a 16-ounce jar of jelly. How many ounces of jelly per sandwich is that?

3. Purslane bought 350 rolls of toilet paper for the whole year. How many rolls of toilet paper per month is that?

4. In the world's longest running experiment, scientists have tried to capture tar pitch dripping on camera. In the past 86 years, 9 drops have formed. How many years per drop is that?

5. Imagine that 12 goats got into a dumpster behind a pizza parlor and ate 3 pizzas. How many goats per pizza would that be?

   

IM Commentary

The purpose of this task is for students to find unit rates in different situations involving unusual units. Most students are familiar with miles per hour, but students are unlikely to have encountered the idea of pumpkins per hippo or goats per pizza. By working with unusual (even silly) units, students must reason abstractly and quantitatively (MP2) in order to answer the questions because they can't rely on their experience with the situation to guide them through it. This will help them later when they study units like kilowatts per square meter and foot-pounds; see also N-Q.1.

The hippo photo was taken by Lori Veres of Woodland Park Zoo.

For more on the tar pitch drop experiment, click here.

The pizza goat was found on the Smithsonian National Zoological Park website.

Solution

1. If 3 hippos eat 5 pumpkins, that is $\frac53$ pumpkins per hippo.

2. If Lindy made 24 jelly-bread sandwiches with 16 ounces of jelly, that is $\frac{16}{24}$ or $\frac23$ ounces of jelly per sandwich.

3. 350 rolls of toilet paper for the whole year translates to $\frac{350}{12}$ or $29\frac16$ rolls per month.

4. Nine drops in 86 years is $\frac{86}{9}$ or $9\frac59$ years per drop; this is about 9 years and 7 months per drop.

5. If 12 goats eat 3 pizzas, that is $\frac{12}{3}$ or 4 goats per pizza.