Q&A - P3 Math

[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. :?:

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

Solution for 1.


Lillian spent thrice as much as huiling.
Let Lillian be 3X and Huiling be X
Let Daniel be Y

Raise two equations. One is based on how much H and D spend.

X + Y = 65
Y = 65- X


Second equation will be based on how much D & L spend .

3X + y = 89


Now substitute X to become Y by taking the earlier equation.


3(65-x) + y = 89
195 - 3X + Y = 89
-2y = 89 - 195
2y = 106
y = 53

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

Solution for number 2.


Cost of buying cards:

Need to find out cost per packet (1 packet has 3 cards)

57 divide by 3 = 19 packets

Total cost = 19 X $2
\t = $ 38

Cash received from selling:

5 cards at $4
1 card selling at 4 divide by 5 = $0.80

Cash received = $0.80 X 57 = $45.60


He earns: 45.60 - 38 = $7.60

[Tang]

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

Model
-------
| D |---| $65
| D |---|---|---| $89

2 u --> 89 - 65 = 24
1 u --> 24 / 2 = 12

D --> 65 - 12 = $53

Daniel spent $53.

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

Hi Tang


I like your solution on qs 1. It’s short and simple and the diagram helps.
I would like to try teaching my kids using your method but I’m a bit lost as to how to explain on certain portion.

I understand the top part but stuck in the following:

2 u –> 89 - 65 = 24

I understand where the 2u come from but how to explain why

89-65 =

TIA

[tianzhu]

Hi, hope this helps.


http://farm3.static.flickr.com/2610/3709629694_ac1deda57e_o.jpg\">

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

Awesome tianzhu. Thanks!

[shurley197323]

Hi. thks for all the answer. But all this method is not taught in my girl’s school yet. How about yours ? They donot know "xy" and "1 or 2 units"

Do yr child in P3 already know that in school ?

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

[quote]Hi. thks for all the answer. But all this method is not taught in my girl's school yet. How about yours ? They donot know \"xy\" and \"1 or 2 units\"

Do yr child in P3 already know that in school ?[/quote]Taught in dd school. Should be as around P3 level. I'm not sure but some question take a while for me to think.

Not taught at ds school but he is in P2.

[Tang]

There is a new P4 Maths Blog for P4 pupils. You may want to make full use of it.


http://p4mathsquestions.blogspot.com/