My Math Forum Multiplication or Division in Daily Life Problem Which Involves Negative Number

 Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion

October 23rd, 2014, 03:10 PM   #11
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Quote:
 Originally Posted by Denis If you want (as example) to teach how to divide 1000 by -77, why do you want to create a useless "word problem story", as generally seems to be the case way too often as far as I'm concerned.
Because of this:
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 October 23rd, 2014, 04:14 PM #12 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038 Good luck.
 October 23rd, 2014, 08:01 PM #13 Senior Member   Joined: Jul 2014 From: भारत Posts: 1,178 Thanks: 230 $\displaystyle \underline{\textbf{Since the problem should be for Middle Schoolers ,}}\\$ $\displaystyle \textbf{Suppose you are going to school (by any vehicle). }\\ \textbf{When you are about to reach the school, breaks are applied.}\\ \textbf{Calculate the acceleration (not retardation) When the breaks are applied.}$ $\displaystyle \color{green}{\textbf{The above problem involves negative-number-division.}}$ $\displaystyle \color{blue}{\textbf{The same problem can be changed a bit to give an example of negative-number-multiplication.}}$ $\displaystyle \textbf{Suppose your school bus starts from your school and }\\ \textbf{reaches your home to pick you up and drops you to school }\\ \textbf{and then goes even further till point C (not towards your home)}\\ \textbf{The Displacement from school to point C has to be negative.}\\ \textbf{So, calculate that displacement.}$ Last edited by Prakhar; October 23rd, 2014 at 08:13 PM.
October 24th, 2014, 04:40 AM   #14
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Quote:
 Originally Posted by prakhar $\displaystyle \underline{\textbf{Since the problem should be for Middle Schoolers ,}}\\$ $\displaystyle \textbf{Suppose you are going to school (by any vehicle). }\\ \textbf{When you are about to reach the school, breaks are applied.}\\ \textbf{Calculate the acceleration (not retardation) When the breaks are applied.}$ $\displaystyle \color{green}{\textbf{The above problem involves negative-number-division.}}$ $\displaystyle \color{blue}{\textbf{The same problem can be changed a bit to give an example of negative-number-multiplication.}}$ $\displaystyle \textbf{Suppose your school bus starts from your school and }\\ \textbf{reaches your home to pick you up and drops you to school }\\ \textbf{and then goes even further till point C (not towards your home)}\\ \textbf{The Displacement from school to point C has to be negative.}\\ \textbf{So, calculate that displacement.}$
Doesn't the above problem involve fraction-number-division instead?
Thanks for the suggestion below that, though.

 October 24th, 2014, 05:38 AM #15 Senior Member   Joined: Apr 2014 From: Glasgow Posts: 2,164 Thanks: 736 Math Focus: Physics, mathematical modelling, numerical and computational solutions I considered problems that follow Prakhar's suggestion before, but I think students might be tempted to work with deceleration (positive), rather than acceleration (negative), and then modify their final result by placing a negative sign. Furthermore, physics questions like these are probably too difficult for kids who are just learning negative numbers for the first time. I really like the idea Fysmat came up with, which is to base a question on stuff used by computers, like the left margin in a word processor. i) Daniel is writing a report in a word processor. The left margin is currently placed at a position of -1.5cm. Daniel wants to move the margin to a new position that is three times further away to the left from zero. What is the new position of the margin? ii) Daniel places 6 tick marks on the diagram between the margin's new position and 0cm. What is the position of the first tick mark the left of the one at 0cm? For questions like this, it would be much better to have a diagram so the student is clear what is happening and the question tests the student on his ability to perform the negative number calculations rather than figure out what's going on. I recommend forgetting real life and instead have a computer game question... Ryu gets hit by a laser attack from Dr Evil and his hit points change by -15. Oh no! Dr Evil makes another attack with the laser, but Ryu now puts up a shield that reflects some of the laser beam back at Dr Evil. If Dr Evil does three times less damage to Ryu because of the shield, what do Ryu's hit points change by? What do Dr Evil's hit points change by if he gets hit by the reflected blast? You could even set an assignment which is to draw the epic fight scene between Ryu and Dr Evil on a piece of paper, but only within the margins calculated by the first question! Thanks from Monox D. I-Fly Last edited by Benit13; October 24th, 2014 at 05:47 AM.
October 24th, 2014, 06:10 AM   #16
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Quote:
 Originally Posted by Benit13 I recommend forgetting real life and instead have a computer game question... Ryu gets hit by a laser attack from Dr Evil and his hit points change by -15. Oh no! Dr Evil makes another attack with the laser, but Ryu now puts up a shield that reflects some of the laser beam back at Dr Evil. If Dr Evil does three times less damage to Ryu because of the shield, what do Ryu's hit points change by? What do Dr Evil's hit points change by if he gets hit by the reflected blast? You could even set an assignment which is to draw the epic fight scene between Ryu and Dr Evil on a piece of paper, but only within the margins calculated by the first question!
Actually, that is a neat idea and I like it. Just hope that the head-editor will allow me to use computer game as example.

 October 24th, 2014, 06:29 AM #17 Math Team   Joined: Oct 2011 From: Ottawa Ontario, Canada Posts: 14,597 Thanks: 1038 Wild idea, probably stupid: golf, where one of +, 0 or - must be used...
October 24th, 2014, 06:38 AM   #18
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Quote:
 Originally Posted by Denis Wild idea, probably stupid: golf, where one of +, 0 or - must be used...
This is a great idea! A negative score in golf means you are doing really well, so that would work nicely.

May 23rd, 2016, 11:06 PM   #19
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Quote:
 Originally Posted by Benit13 This is a great idea! A negative score in golf means you are doing really well, so that would work nicely.
Sorry for necro-posting, but how does a negative score in golf means you are doing really well? What are the rules?

May 24th, 2016, 01:35 AM   #20
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Quote:
 Originally Posted by Monox D. I-Fly Sorry for necro-posting, but how does a negative score in golf means you are doing really well? What are the rules?

Basically, in Golf, each hole has a par, which is an average number of shots for someone to finish it. In general, par 3 holes tend to be quite small, par 4 holes are normal and par 5 holes tend to be the largest/most difficult ones.

Now, let's say you complete the first par 4 hole in 3 shots. That means you beat the par by 1 (a "birdie"), so your total score becomes -1. If you complete the next hole, which is par 5, in 4 shots, then your score becomes -2. Then you keep going, trying to complete each hole in as fewest shots as possible.

By the end of the course (usually 9 or 18 holes), all players will have a range of scores spanning the negative and positive numbers. The player with the lowest score win the course.

Therefore, a set of golf scores can be used by a teacher to set negative number questions. You could give a table of player's scores and ask for the difference (or whatever) between two player's scores.

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