Interpreting a tape diagram to find percent increase
At about 78-90s the narrator says the tomato plant is 40% (two fifths) of the zucchini plant's height; it is actually 140% of it (40% taller). The final answer of 40% taller is correct, and a note was added to correct the slip.
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A tape diagram compares a tomato plant's height (7 units) to a zucchini plant's height (5 shaded units). The tomato plant is 2 units, or 2/5 = 40%, taller than the zucchini plant.
You'll be able to
- read a tape diagram to compare two quantities.
- find a percent increase as the extra part divided by the starting amount.
- convert 2/5 to 40%.
Key words
- Tape diagram
- A drawing of equal-sized boxes used to compare amounts.
- Percent increase
- How much bigger something is, as a percent of the starting amount.
Transcript
- [Instructor] Amara measures the height of her tomato plant and her zucchini plant. The tape diagram shows how the height of the tomato plant relates to the height of the zucchini plant. All right, so if this whole thing is the tomato plant height, the part that is shaded in is the zucchini plant height.
Use the tape diagram to describe the height of the tomato plant relative to the height of the zucchini plant. Well, the tomato plant's clearly larger than the zucchini plant, and let's see, they want us to figure out a percentage. The tomato plant is blank percent taller or shorter than the zucchini plant.
So we already know it's taller. You can even see that visually. The tomato plant is the whole thing, while the zucchini plant is just the shaded part. So if I was using this dropdown, I would pick taller, but what percent taller is it? Well, we can see the zucchini plant is one, two, three, four, five units, and the tomato plant is two more of those units, so whatever two out of five is, that's the percent increase to go from the zucchini plant to the tomato plant.
So two over five, you might recognize that's the same thing as four over 10 or 40 over a hundred, which is equal to 40%. So the tomato plant, this right over here, is 40% of the zucchini plant's height, and that's the same thing as two fifths of the zucchini plant's height, which you can see very clearly from that tape diagram.
So the tomato plant is 40% taller than the zucchini plant. And we are done.
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