Q&A - PSLE Math

[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)

[tianzhu]

Hi, small


I guess you just wanted to check the answer. It is $69.60.
1 kg of beef ----- 7.2
1 kg of venison -----12

[Muffins]

small,


venison beef working:
$8.64 = 120% 1kg beef
$8.64 divided by 120% equals $7.20 which is 1kg of beef
$7.20 multiplied by 2 = $14.40 which is 120% of 1kg venison
$14.40 divide by 120% = $12
$12 multiplied by 4 = $48
$7.20 multiplied by 3 = $21.60

$48 + $21.60 = $69.60

Hope my ans. is correct!

[Dharma]

tianzhu:

Hi, small


I guess you just wanted to check the answer. It is $69.60.
1 kg of beef ----- 7.2
1 kg of venison -----12

Hi Tianzhu,

Got a different answer .... is it something to do with the \"120% more\"?

120% - $8.64
100% - $7.20 (1kg of beef)

220% - $14.40 (2kg of beef)
100% - $ 6.55 (1kg of venison)

4kg venison + 3 kg beef = 4x$6.55 + 3x$7.20 = $47.80 ($47.78 if use calculator)

[tianzhu]

Hi Dharma


Thanks for the correction.I made a mistake.(use 20% more instead of 120% more)
Price of venision per kg should be $6.55.
Price of beef per kg is $7.20.
Best wishes.

Hi small
Please consider my earlier post as null and void.
The answer is $47.80.
Best wishes

[Muffins]

Hi Dharma and Tianzhu,


The answer I got was also $69.60!

Could you pls show me how the answer is $47.80 (or $47.78 ) and why my answer is wrong? :?

Thanks in advance.

Muffins.