How Much did the Tree Grow?Date: 11/07/2001 at 19:46:11 From: Robert Blokzyl Subject: Subtracting 2-Digit Numbers A white pine was 16 m tall in 1962. It was 20 m tall in 1965. It is now 34 m tall. How much has it grown since 1962? I added 16 and 20 and 34 and subtracted that from 16. The answer is 54. I am not sure if that is correct. It doesn't seem right to me. Date: 11/08/2001 at 12:39:46 From: Doctor Ian Subject: Re: Subtracting 2-Digit Numbers Hi Robert, Sometimes a picture can help: Growth since 34m 1962 | | | | 20m | | 16m | | | | | | | | | | | | | | | 1962 1965 now In fact, it makes no difference how tall the tree was in 1965. The relevant information in the problem is A white pine was 16 m tall in 1962. It is now 34 m tall. How much has it grown since 1962? That's part of what this problem is supposed to teach you - that sometimes a problem will contain information that isn't relevant, e.g., Bob and Sam drove a yellow Mercedes convertible from New York to Los Angeles, a distance of 3900 miles. They stopped for coffee 28 times, and stopped to use restrooms 19 times. They spent $125 on food, and listened mostly to the Beach Boys and Nirvana while driving. They were stopped for speeding twice, but were able in each case to talk the police officer out of giving them a ticket. The price of gas varied between $1.29 and $1.56 per gallon. If the trip took 78 hours, what was their average speed? This is sort of an extreme example, but the only relevant information is this: Bob and Sam drove a distance of 3900 miles. If the trip took 78 hours, what was their average speed? I hope this helps. Write back if you'd like to talk about this some more, or if you have any other questions. - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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