Q&A - P5 Math

[MathIzzzFun]

vsk:

Hi everyone, i would like to seek your help in doing this question.


A watch and a pen cost $105. If 3 pens cost $27 more than the watch, find the cost of such 2 watches?

thks :thankyou:

3 pens = 1 watch + $27

1 watch + 1 pen = $105
3 watches + 3 pens = $315
3 watches + (1 watch + $27) = $315
1 watch --> $72

cheers.

[vsk]

Thank you MathIzzzFun for the solution. It really helped. :thankyou:

[vsk]

Hi everyone. I need your help in solving this question.Thks.


The total cost of 9 forks and 5 knives cost $71. the total cost of 3 forks and 3 knives is $33. find the difference in cost between a fork and a knife.





:thankyou:

[AtoZ]

Hi there, I need your help!


In a library, the number of adults was 3/5 of the number of children at first. Then 6 adults and 4 children came in and the number of adults became 3/4 of the number of children. How many people were at the library at first?

Thank you!

[MathIzzzFun]

AtoZ:

Hi there, I need your help!


In a library, the number of adults was 3/5 of the number of children at first. Then 6 adults and 4 children came in and the number of adults became 3/4 of the number of children. How many people were at the library at first?

Thank you!

at first,
adults --> 3 units
children --> 5 units
total --> 8 units

in the end,
adults --> 3 units + 6 = 3 * (1 unit +2)
children --> 4 * (1 unit + 2) = 4 units + 8


4 children added in the end,
so, 5 units + 4 = 4 units + 8
1 unit --> 4

At first, total number of people at the library --> 8 x 4 = 32

cheers.

[AtoZ]

MathIzzzFun:

AtoZ:

Hi there, I need your help!


In a library, the number of adults was 3/5 of the number of children at first. Then 6 adults and 4 children came in and the number of adults became 3/4 of the number of children. How many people were at the library at first?

Thank you!

at first,
adults --> 3 units
children --> 5 units
total --> 8 units

in the end,
adults --> 3 units + 6 = 3 * (1 unit +2)
children --> 4 * (1 unit + 2) = 4 units + 8


4 children added in the end,
so, 5 units + 4 = 4 units + 8
1 unit --> 4

At first, total number of people at the library --> 8 x 4 = 32

cheers.

Many thanks, MathIzzzFun!

Btw, is the question a P5 standard?

[MathIzzzFun]

AtoZ:

MathIzzzFun:

[quote=\"AtoZ\"]Hi there, I need your help!


In a library, the number of adults was 3/5 of the number of children at first. Then 6 adults and 4 children came in and the number of adults became 3/4 of the number of children. How many people were at the library at first?

Thank you!

at first,
adults --> 3 units
children --> 5 units
total --> 8 units

in the end,
adults --> 3 units + 6 = 3 * (1 unit +2)
children --> 4 * (1 unit + 2) = 4 units + 8


4 children added in the end,
so, 5 units + 4 = 4 units + 8
1 unit --> 4

At first, total number of people at the library --> 8 x 4 = 32

cheers.

Many thanks, MathIzzzFun!

Btw, is the question a P5 standard?[/quote]
yes

cheers.

[AtoZ]

MathIzzzFun, I have pm you. Thanks!

[sokk]

Hi,


Need a help for this question from My Pals Are Here Maths Enrichment P5A .

At a Science competition, 25 problems were given. Each correct answer earned 4 points, and 2 points were deducted for each incorrect answer. Liang Hong answered all but one of the problems receiving a score of 66. How many correct answers did she have?


Thanks !

[MathIzzzFun]

sokk:

Hi,


Need a help for this question from My Pals Are Here Maths Enrichment P5A .

At a Science competition, 25 problems were given. Each correct answer earned 4 points, and 2 points were deducted for each incorrect answer. Liang Hong answered all but one of the problems receiving a score of 66. How many correct answers did she have?


Thanks !

You can use Guess & Check or supposition or the area model method...

here's a similar one using area model (which is supposition method in model)- http://www.flickr.com/photos/62167097@N02/7634466300/in/photostream

for your question, need to tweak a little --> total number of questions answered is 24.

all questions answered correctly --> 24 x 4 = 96
96 - 66 = 30 (points lost for questions answered wrongly)
questions answered wrongly --> 30 / (4+2) = 5
questions answered correctly --> 24 - 5 = 19

cheers.