Singapore math help, please!!

[Elaine]

We can't figure this out-

 

Adam bought a pen. He also bought a book which cost 3 times as much as the pen. He spent $112 altogether. Find the cost of the book.

 

Are we just really dumb?

[Jean in Newcastle]

Divide the $112 by 4. (The book is 3 parts of the total, the pen is 1 part).

[Alana in Canada]

Use the rectangle "diagram". It represents the total $112.00

 

Then the pen is one unit (section off the box)--and the book is three of the same sized units.

 

There are a total of four units: so just divide 112 by 4.

 

The first time we saw one of these I was thrown for a mini-loop, too. The diagram was a great way to help explain it to ds.

 

I hope that was clear!

[Sputterduck]

84 I think

[Elaine]

Thank-you!

 

Don't I feel like a big moron.:tongue_smilie:

[Kate in Arabia]

Singapore is big on setting up bar/graphs, we use the term "segments":

 

pen = 1 segment

book = 3 times as much as the pen, so 3 segments

 

he spent $112 altogether, and altogether has 3+1 = 4 segments; so divide 112 into 4 segments:

 

112/4 = 28

 

so each segment is 28, therefore:

pen = 1 segment = $28

book = 3 segments = 3x28 = $84

[Jean in Newcastle]

Don't feel like a moron! I've been stumped many times by problems like that!

[ljf]

I get $84.

 

(cost of pen) + (cost of book) = $112

(cost of pen) + 3*(cost of pen) = $112

4*(cost of pen) = $112

(cost of pen) = $28

 

(cost of book) = $112 - (cost of pen)

(cost of book) = $84

[Jenn in Mo]

That is one expensive book.

[Elaine]

That is one expensive book.

 

:lol:

[dawn of ns]

That is one expensive book.

 

He's taking a caligraphy course. He had to buy a good quality fountain pen and the text for the course.:001_smile:

[WTMindy]

Don't feel dumb! Singapore teaches a different way to think about math problems. That is one thing I really like about it!! There are times when I am stumped at how to set up a diagram and I was a math major. I have to solve the problem algebraicly and then go back and figure out how to set up the bars. But, I would encourage you to practice on those bar problems because they get harder and harder, but they allow students to do complicated mathematical problems without needing to know algebra yet. Good stuff!!