How to Interpret "Increase" in Word Problems
Date: 10/19/2004 at 07:02:43 From: Sonia Subject: What is 3.7 increased by 1/10 I have tried the question to increase 3.7 by 1/10, but my answer has not increased, it's decreased from 3.7 to 0.37. I got this by doing 3.7 x 1/10. Please explain this to me.
Date: 10/19/2004 at 09:41:36 From: Doctor Peterson Subject: Re: What is 3.7 increased by 1/10 Hi, Sonia. The phrase you are answering is one that is very easy to confuse with similar phrases. If I say "multiply 3.7 by 1/10", I mean 3.7 * 1/10 = 0.37. Note that we don't use the word "increase" to talk about multiplication, even though multiplying by a number greater than 1 does increase a number. The word is reserved for addition, as in the next case. If I say "increase 3.7 by 0.1", I probably mean 3.7 + 0.1 = 3.8. To increase a number is to add something (positive) to it. If I say "increase 3.7 by 1/10" (or, more often, "by 10%"), I mean to add a tenth OF 3.7 TO 3.7. That is, 1/10 of 3.7 is 0.37, and I want to increase 3.7 by that amount: 3.7 + 0.37 = 4.07. The last of these is what you were asked for. If you have any further questions, feel free to write back. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.