Q&A - PSLE Math

[Budo]

Hi need help in this question


Andrew and Brian had some money
If Andrew gave Brian $55, the ratio of Andrew to Brian amount is 3:5.
If Brian gave Andrew 20% of this money and $10, Andrew would have $108 more than Brian.
How much do Andrew and Brian have at first?

[Maths Monster]

sokmun98:

Muthu and Beng Huat had some money. If Muthu gave Beng Huat $360, both would have equal amount of money. If Beng Huat gave Muthu $180, Beng Huat would have 1/3 as much money as Muthu.

a) How much money did Muthu have?
b) How much money did Beng Huat have?

Pls help. TIA ..

After M gave B $360:
M [u]
B [u]

Before M gave B $360:
M [u+360]
B [u-360]

B gave M $180:
M [u+360+180]
B [u-360-180]

B would have 1/3 as much money as M:
(u-360-180) x 3 = u+360+180
3u-1620=u+540
u=1080

Therefore,
a) M has u+360 = 1080+360 = $1440
b) B has u-360 = 1080-360 = $720

Check:
B gave M $180:
M = 1440+180 = 1620
B = 720-180 = 540 => 1/3 of M

[Maths Monster]

abc_parent:

Hi everyone, can I just check whether the answer is correct to this question?


Alan, Ben and Charles had 864 trading cards. Ben won some of the cards from Alan and as a result, Ben's cards increased by 50%. Charles then won some cards from Ben and Charles' cards increased by 40%. Finally, Charles lost some of his cards to Alan and Alan's cards increased by 20%. In the end, they realised that they each had an equal number of cards. How many cards did Alan have at first?

Ans: 368

I got
Alan: 432
Ben: 192
Charles: 240

I am quite sure my answer is correct....can someone explain step by step?
Thanks a lot in advance!!!

Work backward:
In the end, they realised that they each had an equal number of cards. Each has 864/3=288
A = 288
B = 288
C = 288

Charles lost some of his cards to Alan and Alan's cards increased by 20%.
A = 288/1.2 = 240
B = 288
C = 288 + (288-240) = 336

Charles then won some cards from Ben and Charles' cards increased by 40%.
A = 240
C = 336/1.4 = 240
B = 288 + (336-240) = 384

Ben won some of the cards from Alan and as a result, Ben's cards increased by 50%.
B = 384/1.5 = 256
A = 240 + (384-256) = 368
C = 240

Therefore, A has 368 at first

[abc_parent]

Thanks to Maths Monster!!

[abc_parent]

Hi everyone,

Q13,15 contain diagrams. Please help if you have the exam paper.

Q13) The diagrm below shows 3 identical circles embedded in a rectangle. Given that the length of the rectangle is 18cm, find the total area of the shaded parts. Use a calculator to obtain the value of pi. (Give your answer correct to 2 decimal places)

–> I don’t understand in the solution provided:
18cm / 3 = 6cm
Big triangle -> 18 x 6.5 = 54
6cm / 2 = 3cm
1 circle -> 3 cm x 3cm x pi = 9pi
54-9pi = 25.725 [why minus area of 1 circle only?]


Q14) Audrey and Belle have some money each. If Audrey spends $18 and Belle spends $24 each day, Audrey will still have $25 left when Belle has spent all her money. If Audrey spends $13 and Belle spends $30 each day, Audrey will still have $139 left when Belle has spent all her money. How much money do they have altogether?

Ans:$655

Q15)The series of figures below are made of cubes. Study the diagram below and answer the following questions.
(a) How many cubes will there be in Figure 6?
(b) Which figure will have 120 cubes?

Ans: 56
Ans: Figure 8

–> I don’t understand the series.Can someone explain, please?

Q17) Yusof has a total of 560 local and foreign stamps. After giving away 80% of the local stamps and 50% of the foreign stamps, he had 172 stamps left.
(a) How many local stamps did he have at first?
(b) How many foreign stamps did he give away?

Ans: (a) 360
(b) 100

[Maths Monster]

abc_parent:

Hi everyone,


Q17) Yusof has a total of 560 local and foreign stamps. After giving away 80% of the local stamps and 50% of the foreign stamps, he had 172 stamps left.
(a) How many local stamps did he have at first?
(b) How many foreign stamps did he give away?

Ans: (a) 360
(b) 100

Yusof has a total of 560 local and foreign stamps.
L + F =560

After giving away 80% of the local stamps and 50% of the foreign stamps, he had 172 stamps left.
1/5L + 1/2F = 172

If we multiply by 2:
2/5L + F = 344

We can see that:
3/5L = 560-344
L=360

F=200
He gave away 50% of the foreign stamps which is 0.5x200=100

[tianzhu]

Hi

Hope this helps.

http://farm5.static.flickr.com/4137/4773175314_04b721ac8f_b.jpg\">

Best wishes

[Maths Monster]

abc_parent:

Hi everyone,


Q14) Audrey and Belle have some money each. If Audrey spends $18 and Belle spends $24 each day, Audrey will still have $25 left when Belle has spent all her money. If Audrey spends $13 and Belle spends $30 each day, Audrey will still have $139 left when Belle has spent all her money. How much money do they have altogether?

Ans:$655

If Audrey spends $18 and Belle spends $24 each day, Audrey will still have $25 left when Belle has spent all her money.

Let u be the number of days in this case.

A [18u][25]
B [24u]

If Audrey spends $13 and Belle spends $30 each day, Audrey will still have $139 left when Belle has spent all her money.

A [18u-114][139]
B [24u]

The ratio of [18u-114] and [24u] is 13:30, we can write the equation:
(18u-114)x30 = (24u)x13
540u-3420=312u
228u=3420
u=15

Therefore,
A = 18u+25 = $295
B = 24u = $360
Total = $655

Check:
If Audrey spends $18 and Belle spends $24 each day, Audrey will still have $25 left when Belle has spent all her money.
A = (295-25)/18 = 15 days
B = 360/24 = 15 days

If Audrey spends $13 and Belle spends $30 each day, Audrey will still have $139 left when Belle has spent all her money.
A = (295-139)/13=12 days
B = 360/30 = 12 days

[Maths Monster]

Budo:

Hi need help in this question


Andrew and Brian had some money
If Andrew gave Brian $55, the ratio of Andrew to Brian amount is 3:5.
If Brian gave Andrew 20% of this money and $10, Andrew would have $108 more than Brian.
How much do Andrew and Brian have at first?

If Andrew gave Brian $55, the ratio of Andrew to Brian amount is 3:5.
A [3u]
B [5u]

At start,
A [3u+55]
B [5u-55]

If Brian gave Andrew 20% of this money and $10, Andrew would have $108 more than Brian. 20% of 55 + 10 = $21
A [3u+55+21] = [3u+76]
B [5u-55-21] = [5u-76]

We can write the equation:
3u+76-108 = 5u-76
2u = 44
u =22

Therefore, at first,
A = 3u+55 = $121
B = 5u-55 = $55
Total = $176

[hamsterss]

livewith_vanilla:

hamsterss:

[quote=\"ruyu\"]

[/quote]
Really? I saw the Maths Workbook 6B's answer key wrote the answer as :

1000+2000=3000km [Example]

Is it okay since the answer key in the Maths Workbook 6B wrote it this way?

One more :oops:

Can i just write :

100m + 3km = 3.1km? even though the unit is not the same?

Thanks