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Calling all math minded people. HELP!


Ohdanigirl
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Ds is having such a hard time with this problem. He has worked other ones like it with me and been able to follow and explain what should be done, but he just can't solve the following problem. He just goes blank and stares at it.

 

Davina, Jean, and Nancy have a total savings of $4800. If Davina saves $480 more than Nancy and Jean saves $330 less than Davina, how much does Jean save?

 

Maybe I need a different way of explaining it to him? I would love your ideas and maybe a step by step process to go through with him. I have tried my way and he obviously needs a fresh outlook. Please help.

 

Thanks.

Danielle

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Davina, Jean, and Nancy have a total savings of $4800. If Davina saves $480 more than Nancy and Jean saves $330 less than Davina, how much does Jean save?
Are you using bar diagrams?

 

Nancy

Davina ($480 more than Nancy)

Jean (Davina less $330 = Nancy + $150)

 

========|

========|=========$480====|

========|==$480-$330==|

...........................=$150

 

The three girls have a total of $4800.

 

So:

========|========|========|=========$480====|==$150==|

is equal to $4800

 

 

========|========|========|=========$630============|

is equal to $4800

 

 

========|========|========|

is equal to $4800 - $630 = $4170

 

 

========|

is equal to $4170/3 = $1390

 

 

So Jean was:

========|====$150====|

$1390 + $150 = $1540

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I think what is different about this problem is setting up who is the unit and putting the other two in terms of that unit. Most of the basic Singapore problems have the 2nd and 3rd person in terms of the 1st person. This time the 2nd person is in terms of the 1st but then the 3rd is in terms of the 2nd so you have to do two steps to figure out the 3rd person relationship to the 1st. There is more than one way to solve it and I set it up with Divinia as the unit and with Nancy as the unit and got the same answer both ways.

 

I think this is where drawing the bars is helpful in playing with the problem and figuring out who has more money and who has less. If he knows the basics of how to solve this kind of problem, just sit down and start looking out how the people relate to each other and he will see it is the same kind of problem, just an extra step.

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So:

D=N-480

J=D-330

so J=(N-480)-330

 

(N-480) + (N-480-330) + N = 4800

3N - 1290 = 4800

3N = 6090

N = 2030

 

So Nancy had $2030, Davina had $1550, and Jean had $1220.

Davina saved more than Nancy.

 

D=N+480

J=D-330

J=(N+480)-330

 

(N+480) + (N+480-330) + N = 4800

3N + 630 = 4800

3N = 4170

N = 1390

 

Nancy had $1390, Davina had $1870, Jean had $1540.

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Ds is having such a hard time with this problem. He has worked other ones like it with me and been able to follow and explain what should be done, but he just can't solve the following problem. He just goes blank and stares at it.

 

 

If they're able to work other similar problems, sometimes what works is rewriting the one they are stuck on so it's a similar type problem but not recognizable--different numbers, different situation, etc. Sometimes that's enough to shake them out of stuck mode. :)

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thanks everyone. He is familiar with and likes the bar graphs, so I start fresh with those this morning. We did the Algebraic method, but he just didn't like it with his problem. I am confident he will do better today now that he has had some sleep and is starting fresh. I will keep you all posted on this.

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Are you using bar diagrams?

 

 

Thank you for the example :001_smile:

 

I was reading through my 6 volume stash of "Complex Word Problems" (purchased prior to them going out-of-print, thanks to you) last night, and I realize I REALLY have to get good at these :D

 

Anyway, when I saw the example, rather than going algebraic I used the bar diagram method. And then it was great to check myself against your example (and to see I'd applied it correctly :lol:).

 

I'm seeing "bar diagramming" will soon become a "life-style." :tongue_smilie:

 

Bill

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