heart'sjoy Posted May 26, 2010 Share Posted May 26, 2010 Can anyone show us how to draw the bar diagrams for this sm problem ? I've filled 4 sheets of graphpaper and still don't see the units. 4 books and 5 magazine cost $103.60 altogether. 8 books and 3 magazines cost $134.40 altogether. How much less does each magazine cost than each book? Quote Link to comment Share on other sites More sharing options...
swainsonshawk Posted May 26, 2010 Share Posted May 26, 2010 I'm trying to solve it with algebra and I can't even do that. Still working. . . :tongue_smilie: Quote Link to comment Share on other sites More sharing options...
Ali in OR Posted May 26, 2010 Share Posted May 26, 2010 What problem is it? Just looking at what you wrote and not our book, I bet we doubled the first equation to 8 books and 10 magazines cost $207.20. Then since both equations have 8 books, the only difference in cost is due to 7 more magazines in the first and use that to figure out the cost of one magazine. That's a very algebraic approach--not sure if we did a bar diagram or not. Quote Link to comment Share on other sites More sharing options...
Dana Posted May 26, 2010 Share Posted May 26, 2010 What problem is it? Just looking at what you wrote and not our book, I bet we doubled the first equation to 8 books and 10 magazines cost $207.20. Then since both equations have 8 books, the only difference in cost is due to 7 more magazines in the first and use that to figure out the cost of one magazine. That's a very algebraic approach--not sure if we did a bar diagram or not. It's CWP 4 p82 #23. I'm looking at it and not figuring it out :) I'd set up a system of equations: 4b + 5m = 103.60 8b + 3m = 134.40 Doubling the first eqn and finding the difference will solve for a magazine price. No idea how to use bar diagrams. I'll be curious to see how it works out! Quote Link to comment Share on other sites More sharing options...
swainsonshawk Posted May 26, 2010 Share Posted May 26, 2010 I bow to the math nerds on this site. I'm not coming up with a nice number. Maybe I've forgotten my algebra. :glare: I even tried doubling the equation and all. I don't have any idea how you'd translate this into a bar diagram for a kid. I'm so glad I don't have the kids doing CWP. It's too hard for me! Quote Link to comment Share on other sites More sharing options...
manylilblessings Posted May 26, 2010 Share Posted May 26, 2010 IDK about the bar diagram approach. I'd use the PP's system. And the answer I got was a $2.50 difference. Maybe the bars would show the visual of doubling them, to find the magazine price. Quote Link to comment Share on other sites More sharing options...
NicksMama-Zack's Mama Too Posted May 26, 2010 Share Posted May 26, 2010 (edited) 4 books and 5 magazine cost $103.60 altogether. 8 books and 3 magazines cost $134.40 altogether. How much less does each magazine cost than each book? I would double the first scenario: 8 books and 10 magazines cost $207.20 The difference between this 8:10 and the acutual 8:3 is 7 units/magazines. You would see this if you drew the original 4:5 and then drew the 8:3 ratio. You need to keep the ratio the same to figure out the problem. difference in cost is 207.20-134.40 is 72.8. Divide this by the number of units that are different between the doubled scenario and the actual (7) to get a single unit (10.40 per magazine). In the original equation, 5 would cost 52.00 and the 4 books would cost (103.60-52)/4 = 12.90. So each book cost $2.50 more than each magazine. I'm probably not explaining this clearly, but these CWP problems require a lot of mental/logic to figure out. Edited May 26, 2010 by NicksMama-Zack's Mama Too Quote Link to comment Share on other sites More sharing options...
Corraleno Posted May 26, 2010 Share Posted May 26, 2010 [———————$207.20———————] |———8B———|————10M————| [——$134.40————] |———8B———|—3M| |———————————[——$72.80—] |———————————|———7———| 72.80/7 = $10.40 cost per magazine 8B + 3(10.40) = 134.40 8B + 32.10 = 134.40 B = 103.20/8 = $12.90 cost per book Cost difference = $2.50 Jackie Quote Link to comment Share on other sites More sharing options...
NicksMama-Zack's Mama Too Posted May 26, 2010 Share Posted May 26, 2010 [———————$207.20———————]|———8B———|————10M————| [——$134.40————] |———8B———|—3M| |———————————[——$72.80—] |———————————|———7———| 72.80/7 = $10.40 cost per magazine 8B + 3(10.40) = 134.40 8B + 32.10 = 134.40 B = 103.20/8 = $12.90 cost per book Cost difference = $2.50 Jackie :) Very Nice! Quote Link to comment Share on other sites More sharing options...
Ali in OR Posted May 26, 2010 Share Posted May 26, 2010 Those are beautiful bar diagrams Jackie! And on a computer no less. Quote Link to comment Share on other sites More sharing options...
Jen S in Va Posted May 27, 2010 Share Posted May 27, 2010 [———————$207.20———————]|———8B———|————10M————| [——$134.40————] |———8B———|—3M| |———————————[——$72.80—] |———————————|———7———| 72.80/7 = $10.40 cost per magazine 8B + 3(10.40) = 134.40 8B + 32.10 = 134.40 B = 103.20/8 = $12.90 cost per book Cost difference = $2.50 Jackie Boy, that makes it look so easy! Quote Link to comment Share on other sites More sharing options...
heart'sjoy Posted May 27, 2010 Author Share Posted May 27, 2010 [———————$207.20———————]|———8B———|————10M————| [——$134.40————] |———8B———|—3M| |———————————[——$72.80—] |———————————|———7———| 72.80/7 = $10.40 cost per magazine 8B + 3(10.40) = 134.40 8B + 32.10 = 134.40 B = 103.20/8 = $12.90 cost per book Cost difference = $2.50 Jackie Many thanks Quote Link to comment Share on other sites More sharing options...
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