asheslawson wrote:IP 5A, pg 14, #10

This one, from Intensive Practice 5A, is stumping us! I am also doing 5A textbook along with 5A Intensive Practice. I also have the HIG from Sonlight - which is helpful if I'm stumped on a problem in the TB or WB, but there is not help for IP!

How do I help my son solve:

**Tim & Shelly have a total of 3450 coins in their piggy banks. Shelley & Nina have a total of 5130 coins. Nina has 5 times as many coins as Tim. How many coins does Shelley have? **
I posted to Singapore's forum for this problem & #9 as both left me clueless. The responder was VERY helpful with #9. However - this one does not make sense - I'm trying to get it un-muddled in my head - but I'm clueless! Here is what she sent me....

"Have you done the Primary Mathematics? The Standards edition HIG has a lot of pointers. Or you could do Process Skills at a lower level until they become more familiar. This one is like one in the 5A textbook, are you doing that?

Nina has 5 times as much as Tim

|----| Tim

|----|----|----|----| Nina

Now add Shelley to both. I am going to add her to the beginning. The point is that the difference stays the same if you add the same to both.

|---------|----| Shelley and Tim = 3450

|---------|----|----|----|----| Shelley and Nina = 5130

Can you see that the difference is 3 units and solve from there? "

I have 3 issues...

First: I still don't get it. I have the answer in my IP answer section - but I don't see how to find it.

Second: based on the other problem when a skirt that cost 4 times the blouse in her response was represented by 4 units - THEN in this problem, with Nina having 5 times as much as Tim - shouldn't Nina be represented by 5 units?

Third: How does she know to show Shelley & Tim (with 3450 coins) as 2 units & Shelley & Nina (with 5130 coins) with 5 units?

I know this is a LOT - but I am feeling so much like my head is full of concrete & it isn't letting this in!

Aw, hugs for your spinning brain.

I like to just do stream-of-consciousness typing, the way I would think thru a problem on the marker board with my son. Then maybe I'll end up with diagrams similar to hers... or not.

So, I start with the beginning,

*Tim & Shelly have a total of 3450 coins in their piggy banks. *
/---Tim---/---Shelly---/ = 3450 coins

Nothing very helpful there, we don't even know if the bars are equal.

So moving on to the next piece.

*Shelley & Nina have a total of 5130 coins.*
/---Shelley---/---Nina---/ = 5130 coins

Again, not too helpful, we don't know if they're equal, but I've gotta start somewhere, so I draw everything and keep those drawings in case they help later.

Next,

*Nina has 5 times as many coins as Tim.*
/---Nina---/---Nina---/---Nina---/---Nina---/---Nina---/

/---Tim---/

Okay, this is the first time we know the bars are actually equal to one another.

(By the way, I think the gal above made a typo here - you're right about the 5.)

Now, I don't really have a direction here, but I do know we could plug those bars into the other diagrams and see what we get.

So here are the first 2 diagrams we had.

/---Tim---/---Shelly---/ = 3450 coins

/---Shelley---/---Nina---/ = 5130 coins

I'm wondering where I could plug in those "truly equal" Tim/Nina bars from the 3rd diagram?

Okay, I'll try subbing in Nina for Tim:

/---(1/5 of Nina)---/---Shelly---/ = 3450 coins

/---Shelley---/---Nina---/ = 5130 coins

Naw, I don't like that, the fraction gives me a headache to think past that.

Let me try the other way, subbing in Tim for Nina:

/---Tim---/---Shelly---/ = 3450 coins

/---Shelley---/---Tim---/---Tim---/---Tim---/---Tim---/---Tim---/ = 5130 coins

Do you see how I could exchange "Nina" for 5 Tims, because what she has is 5x as much as Tim? I hope that makes sense to you?!

Okay, now we have Shelly & Tim equal to 3450.

Then we have the difference between 5130 and 3450 equals what? Let me see if I can do it in my head...

3450 (+ 50) = 3500, then (+500) is 4000, then (+1130) is

5130,

so that means the difference is 1680 (50 + 500 + 1130).

Now,

1680 has to be equal to 4 of the Tims, can you spot that?

So, doing it in my head again,

1600 is easily divisible by 4, so that's (400), and 80 divided by 4 is (20), so 420 (400 + 20) must be one Tim.

Okay, it's late and I'd better stop typing until you confirm that 420 is the correct answer in the back of your book? We never did the IP books. I could, of course, check my answer by plugging that back into the original word problem, if I were a good math student

And hopefully others will chime in coming from different angles, and one way of thinking will be something you relate to.

Julie