Q&A - PSLE Math

[tianzhu]

Thank you for your help.


Q45 RGPS SA2 2007 ----- I am referring to the first solution. How to prove that (72+84) equals to half the area of the rectangle?

http://www.wendykoh.com/07/primary6-rgs1-maths.pdf

[atutor2001]

tianzhu:

Thank you for your help.


Q45 RGPS SA2 2007 ----- I am referring to the first solution. How to prove that (72+84) equals to half the area of the rectangle?

http://www.wendykoh.com/07/primary6-rgs1-maths.pdf

The base of both triangles are equal and is equal to the breadth of the rectangle. The sum of the heights of both triangles is equal to the length of the rectangles.

Therefore, their combined areas is equal to half the area of the rectangle.

[faith2u]

Meimei would be given 20cent for each greeting card she sold. In addition, she would get $4 for every 10 greeting cards sold… How many cards did she sell if she earned $80?

[James Ang]

faith2u:

Meimei would be given 20cent for each greeting card she sold. In addition, she would get $4 for every 10 greeting cards sold.. How many cards did she sell if she earned $80?

if she sells 140 cards, she earns (140/10)x6 = 84
if she sells 139 cards, she earns (130/10)x6 +9x20c = 78+1.8 = $79.80

so she could not have earned $80, she is owed $4.

by the way, people smart about maths should also use maths intelligently to make decision. Assuming in above case, if she earns $79.80 selling 139 cards, she should be intelligent enough to know that by selling one more card she earns $4.20 and not $0.20, so logically she should buy that one card herself!

[janice099]

Hello there, this is my first reply. Thanks for helping


John can walk to school in 40 minutes while his brother, Jack, takes 20 minutes. If they both start walking to school at the same time, how long will it take for John to be 2/5 as far as Jack.

[atutor2001]

janice099:

Hello there, this is my first reply. Thanks for helping


John can walk to school in 40 minutes while his brother, Jack, takes 20 minutes. If they both start walking to school at the same time, how long will it take for Jack to be 2/5 as far as John.

Is there something wrong with the question?
Jack is faster than John. Yet the question ask for the time needed for Jack to travel 2 units while John has travelled 5 units.

[Full.010894Cream]

James Ang:

faith2u:

Meimei would be given 20cent for each greeting card she sold. In addition, she would get $4 for every 10 greeting cards sold.. How many cards did she sell if she earned $80?

if she sells 140 cards, she earns (140/10)x6 = 84
if she sells 139 cards, she earns (130/10)x6 +9x20c = 78+1.8 = $79.80

so she could not have earned $80, she is owed $4.

by the way, people smart about maths should also use maths intelligently to make decision. Assuming in above case, if she earns $79.80 selling 139 cards, she should be intelligent enough to know that by selling one more card she earns $4.20 and not $0.20, so logically she should buy that one card herself!

unless the card cost more than $4!

[janice099]

atutor2001:

janice099:

Hello there, this is my first reply. Thanks for helping


John can walk to school in 40 minutes while his brother, Jack, takes 20 minutes. If they both start walking to school at the same time, how long will it take for Jack to be 2/5 as far as John.

Is there something wrong with the question?
Jack is faster than John. Yet the question ask for the time needed for Jack to travel 2 units while John has travelled 5 units.

thank you atutor2001. i typed the last part wrong. i fixed it now

[James Ang]

Full.Cream:

James Ang:

[quote=\"faith2u\"]Meimei would be given 20cent for each greeting card she sold. In addition, she would get $4 for every 10 greeting cards sold.. How many cards did she sell if she earned $80?

if she sells 140 cards, she earns (140/10)x6 = 84
if she sells 139 cards, she earns (130/10)x6 +9x20c = 78+1.8 = $79.80

so she could not have earned $80, she is owed $4.

by the way, people smart about maths should also use maths intelligently to make decision. Assuming in above case, if she earns $79.80 selling 139 cards, she should be intelligent enough to know that by selling one more card she earns $4.20 and not $0.20, so logically she should buy that one card herself!

right.

unless the card cost more than $4! :D[/quote]

[small]

thanks in advance for your help,


The cost of 2kg of beef is 120% more than the cost of 1kg of venison. 1kg of mutton costs 20% more than the cost of 1kg of beef. If 1 kg of mutton cost $8.64, pls find the total cost of 4kg of venison and 3kg of beef… (given answer is $45.60 while my DD’s answer is $39.60)