Q&A - P3 Math

[corneyAmber]

shurley197323:

[Moderator's note: Topics merged.]


Ben had 338 more bookmarks than Carson.Ben gave some bookmarks to Carson so that Carson had 82 more bookmarks than Ben. How many bookmarks did Ben give Carlson?

Ans: 2 units + 82 = 338 bookmarks
2 units --- 338 -82 = 256 bookmarks
1 unit --- 256 divide 2 = 128 bookmarks
128 + 82 = 210
Ben gave 210 bookmarks to Carlson.

BUT I DID NOT KNOW HOW TO EXPLAIN WHT THE USE THE 2 UNITS TO MY GIRL ? ANYONE HAD OTHER SOLUTIONS ?

(from\" MUST KNOW MATHS PROBLEM SUMS\" PRI 3 FROM EPH)

http://i724.photobucket.com/albums/ww246/ks2me/P3Mathbookmarks-2.jpg\">

[acforfamily]

shurley197323:

[Moderator's note: Topics merged.]


Ben had 338 more bookmarks than Carson.Ben gave some bookmarks to Carson so that Carson had 82 more bookmarks than Ben. How many bookmarks did Ben give Carlson?

Ans: 2 units + 82 = 338 bookmarks
2 units --- 338 -82 = 256 bookmarks
1 unit --- 256 divide 2 = 128 bookmarks
128 + 82 = 210
Ben gave 210 bookmarks to Carlson.

BUT I DID NOT KNOW HOW TO EXPLAIN WHT THE USE THE 2 UNITS TO MY GIRL ? ANYONE HAD OTHER SOLUTIONS ?

(from\" MUST KNOW MATHS PROBLEM SUMS\" PRI 3 FROM EPH)

hi shurley197323,
Perhaps we could think of the 338 being split into 3 blocks, 1 block is the 82 which is what Carlson has more than Ben, the second and third blocks are equal representing what both B and C has after stripping out the 82. These are the 2 units represented in the solution.

[shurley197323]

Thks for the answer. But still trying vey hard to explain.

[corneyAmber]

shurley197323:

Thks for the answer. But still trying vey hard to explain.

Hmm...you mean the model diagram is still tough to explain the solution?

1. The yellow part shows that B & C have same number of bookmarks.
2. The \"peach + pink\" for B is the 338 more bookmarks that B has more than C per the question.
3. Why peach + pink because pink is given away to C so a different colour is used.
4. Then now join the pink to C to show C receive the pink.. ( I should have changed the pink for B in perforated box, to show that it has been given away to C)
5. By fitting the pink block below, we can see that one part of the pink will correspond to the peach box above as SAME UNIT and now C is 82 more than B.

Hope this explains the diagram.

[en107rn.01056yahoo.01056com.01056sg]

Hi shurley197323


Not sure if your child is stil facing problem in understanding the sum.

I have further breakdown the diagram, to assist understanding.
http://www.postimage.org/image.php?v=PqPFNXJ


Therefore Carson has 82 + 128 = 210

If your child still dont understand the explanation, simply take 10 M & M chocolates (as a fictitious number) and ask her to spilt the chocolate between yourself & her. Your daughter has to spilt the chocolate in such a way that she has more by 2. Use smaller number to explain to create understanding.

[Tang]

ks2me:

shurley197323:

[Moderator's note: Topics merged.]


Ben had 338 more bookmarks than Carson.Ben gave some bookmarks to Carson so that Carson had 82 more bookmarks than Ben. How many bookmarks did Ben give Carlson?

Ans: 2 units + 82 = 338 bookmarks
2 units --- 338 -82 = 256 bookmarks
1 unit --- 256 divide 2 = 128 bookmarks
128 + 82 = 210
Ben gave 210 bookmarks to Carlson.

BUT I DID NOT KNOW HOW TO EXPLAIN WHT THE USE THE 2 UNITS TO MY GIRL ? ANYONE HAD OTHER SOLUTIONS ?

(from\" MUST KNOW MATHS PROBLEM SUMS\" PRI 3 FROM EPH)

http://i724.photobucket.com/albums/ww246/ks2me/P3Mathbookmarks-2.jpg\">

Let me try.

At first - Ben had 338 more than Carlson.
Later - Carlson had 82 more than Ben.

1. Remove 338 from Ben, now Ben and Carlson had the same number.
2. From 338, take out 82 - to be given to Ben. Ben now had 82 more than Carlson.
3. The remainer is 338 - 82 = 256. Divide this into 2 portions - 1 for Ben and 1 for Carlson. 1 portion was 256 divide by 2 = 128.

4. So number of bookmarks given to Carlson is 128 + 82 = 210.

------------------------------------------------------------------
This will be easier to explain. Find the big unit instead of finding unit.

2 Big units --> 338 + 82 = 420
1 Big unit --> 420 / 2 = 210.

Explanations
------------
Remove 338 from Ben.
Since now Carlson had 82 more than Ben, split 338 into 1 unit for Carlson and 1 Big unit for Ben.

To find Big unit, it is basically 338 + 82, then divide by 2.

[Tang]

ChiefKiasu:

jedamum:

I'll probably use trial and error method and hope that she is not giving out >100 balloons. :lol:
Ans: 2 students...correct?

That's what we will get when we use algebra, ie. solve for:
6x + 2 = 8x - 2
=> 2x = 4
=> x = 2

Just that the case in question is given the answer of 14 in \"illegal\" black-market exam papers. Shows how bad the answers can be! So don't trust the answers provided.

Also, it is difficult with people not trained to do modelling to work out this problem without algebra.

Using model.

1. Draw 1 unit / box (of 6) + 1 small unit /box (of 2)
2. Below the drawing in (step 1). Draw a dotted small unit / box (of 2) beyond the step 1. Then add 6 to make make a unit (of 8). There is a difference of 2 between steps 1 and 2.
3. Add 1 unit (of 6) to 1st drawing and add 1 big unit (of to 2nd drawing. You notice that they now have equal number.

So total number is 6 x 2 + 2 = 14 or 8 x 2 - 2 = 14.

There are more examples at Uncle Observer's Blog http://www.blogger.com/profile/17918652673297709832 PSLE Maths - Maths Challenging.

[Cavin]

problem Solved !!


Charles had thrice as many stamps as Edward.After Edward collected another 120stamps, he had twice as many stamps as Charles. How many stamps did Charles have?

C=3units
E=1unit

E+120=3units(THRICE E)+2units(Twice E)
therefore 1unit =24
Charles has 24x3=72units

[shurley197323]

THKS .Everyone finally understood.

[shurley197323]

[Moderator's note: Topics merged.]


(1) Hulling & Daniel spent $65 altogether. Daniel & Lilian spent $89 altogether. If Lilian spent thrice as much money as huiling,how much did Daniel spent ?
ANSWER : $53

(2) Mr Yeo bought 57 greeting cards at 3 for $2.He sold them at 5 for $4.
How much money did he earn if he sold all the cards.
Answer : $7.60

SORRY FOR ALL THE TROUBLE. I had the above answer but show no working and this teaches me not to buy assessment without any working show next tme. :?: