Q&A - PSLE Math

[small]

Dharma:

AnnT2009:

Please help,



Q2 Mr Tan bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.40 more than a badge. What is the cost of a badge?
Ans:$1

TIA.

Qty
Badges : 3 units
Toy Cars : 1 unit

Unit Price
Badges : 1 part
Toy car : 1 part + $10.40

Total Value
Badges : (3 units x 1 part)
Toy car : 1 unit x (1 part +$10.40)

(4 units x 1 part) + (1 unit x $10.40) = $144 ------- Eqn 1

(1 unit x $10.40) - (2 units x 1 part) = $84
(2 units x $10.40) - (4 units x 1 part) = $ 168 -------- Eqn 2

Eqn 1 + Eqn 2
(3 units x $10.40) = $ 312
1 unit = 10

40 x 1 part = $144 - $104
1 part = 1

1 part - unit price of badge = $1

Hi Dharma,

Much appreciated if you can elaborate on how to get this:

(1 unit x $10.40) - (2 units x 1 part) = $84

Thanks in advance.

[Dharma]

Hi small,


It's the diff of amount spent on toy cars and badges, ...qn says it is $84

(1 unit) x (1 part +$10.40) - (3 units) x (1 part) = $84
(1 unit)x (1 part) + (1 unit) x ($10.40) - (3 units) x (1 part) = $84
(1 unit) x ($10.40) - (2 units) x (1 part) = $84

Hope it helps ...

[small]

Dharma:

Hi small,


It's the diff of amount spent on toy cars and badges, ...qn says it is $84

(1 unit) x (1 part +$10.40) - (3 units) x (1 part) = $84
(1 unit)x (1 part) + (1 unit) x ($10.40) - (3 units) x (1 part) = $84
(1 unit) x ($10.40) - (2 units) x (1 part) = $84

Hope it helps ...

Hi Dharma,

Thanks...You are great..

Please forgive my ignorance.... :oops:

[tianzhu]

Thank you for your help.


Quite an interesting question, the answer hinges on how we would interpret together took

Mr Yoma and Mr Ula together took 5 hours to paint a room.
Mr Wara and Mr Hito together took 4 hours to paint the same room.
Mr Ula and Mr Wara together took 3 hours to paint the same room.
How long would both Mr Yoma and Mr Hito together take to paint the same room?

Take the case of Mr Yoma and Mr Ula, do you interpret as both men were painting for a total duration of 5 hours. (T1+T2 =5)
or they were painting for 5 hours each (T1=5 and T2 =5)?

[small]

tianzhu:

Thank you for your help.


Quite an interesting question, the answer hinges on how we would interpret together took

Mr Yoma and Mr Ula together took 5 hours to paint a room.
Mr Wara and Mr Hito together took 4 hours to paint the same room.
Mr Ula and Mr Wara together took 3 hours to paint the same room.
How long would both Mr Yoma and Mr Hito together take to paint the same room?

Take the case of Mr Yoma and Mr Ula, do you interpret as both men were painting for a total duration of 5 hours. (T1+T2 =5)
or they were painting for 5 hours each (T1=5 and T2 =5)?

Hi tianzhu,

I will interpret as the both men were painting for a total duration of 5 hours, so the answer is 6 hours???

[Dharma]

small:

tianzhu:

Thank you for your help.


Quite an interesting question, the answer hinges on how we would interpret together took

Mr Yoma and Mr Ula together took 5 hours to paint a room.
Mr Wara and Mr Hito together took 4 hours to paint the same room.
Mr Ula and Mr Wara together took 3 hours to paint the same room.
How long would both Mr Yoma and Mr Hito together take to paint the same room?

Take the case of Mr Yoma and Mr Ula, do you interpret as both men were painting for a total duration of 5 hours. (T1+T2 =5)
or they were painting for 5 hours each (T1=5 and T2 =5)?

Hi Tianzhu and small,

Yoma and Ula took 5 hrs to complete painting the room. T1 + T2 = 5 is not right. You need not bother abt time taken by either Yoma or Ula to paint because their rate of painting are different.

Just take the combinations of times taken by the different groups of men to complete the room.

In 1 hr:
Y+U - 1/5 of room
W+H - 1/4 of room
U+W - 1/3 of room

Therefore, if 4 of them paint together,

In 1 hr:
Y+U+W+H = 1/5 + 1/4 = 9/20 of room

So, Y + H will complete (9/20 - 1/3) = 7/60 of room in 1 hr

So, Y & H will complete painting the room in 60/7hrs

[tianzhu]

small:

I will interpret as the both men were painting for a total duration of 5 hours, so the answer is 6 hours???

The answer is spot on if based on your interpretation.However, the given answer is the same as what Dharma has interpreted.

I am confused.Consider these two sentences.

Mr Yoma and Mr Ula together took 5 hours to paint a room.

Mr Yoma and Mr Ula took 5 hours to paint a room.

Do they have the same meaning in context?Or, do they mean different things?

[Dharma]

tianzhu:

small:

I will interpret as the both men were painting for a total duration of 5 hours, so the answer is 6 hours???

The answer is spot on if based on your interpretation.However, the given answer is the same as what Dharma has interpreted.

I am confused.Consider these two sentences.

Mr Yoma and Mr Ula together took 5 hours to paint a room.

Mr Yoma and Mr Ula took 5 hours to paint a room.

Do they have the same meaning in context?Or, do they mean different things?

From your question, I interprete as with both Mr Yoma and Mr Ula in a room where they (together) took 5 hrs to complete painting the whole room. That's my inpretation of your 1st sentence ...\"together took\"

The 2nd sentence means the same as the 1st one ...I think!!!!

[small]

Hi Dharma,


Once again thanks a lots for the solution…

[Tang]

P6 pupils may want to try the Maths Questions at Uncle Observer's blog


http://prischoolmaths.blogspot.com/