Q&A - PSLE Math

[flying pig]

kwcllf:

Hi, please help with the following question.


John walks to school at an average speed of 4km/h every day. One day, after walking 1km, he realised that his watch was slow. So, he ran at a constant speed to school and reached just on time. Later, he calculated that if he had run at this speed from the start of the journey, he would have reached school 5 minutes earlier. What was his runing speed?

Thanks.

4 km per hour, thus 1 km would take 60/4=15 minutes

since he would have reached school 5 minutes earlier, his running speed would be 15min-5min=10 min taken to run one km.

convert this to km/h and you get 6km/h

[kwcllf]

flying pig:

kwcllf:

Hi, please help with the following question.


John walks to school at an average speed of 4km/h every day. One day, after walking 1km, he realised that his watch was slow. So, he ran at a constant speed to school and reached just on time. Later, he calculated that if he had run at this speed from the start of the journey, he would have reached school 5 minutes earlier. What was his runing speed?

Thanks.

4 km per hour, thus 1 km would take 60/4=15 minutes

since he would have reached school 5 minutes earlier, his running speed would be 15min-5min=10 min taken to run one km.

convert this to km/h and you get 6km/h

Thanks very much for the help :salute:

[kwcllf]

flying pig:

kwcllf:

Hi, please help with the following question.


John walks to school at an average speed of 4km/h every day. One day, after walking 1km, he realised that his watch was slow. So, he ran at a constant speed to school and reached just on time. Later, he calculated that if he had run at this speed from the start of the journey, he would have reached school 5 minutes earlier. What was his runing speed?

Thanks.

4 km per hour, thus 1 km would take 60/4=15 minutes

since he would have reached school 5 minutes earlier, his running speed would be 15min-5min=10 min taken to run one km.

convert this to km/h and you get 6km/h

Thanks very much for the help :salute:

[2DMommy]

MathIzzzFun:

2DMommy:

Please help me with these two questions :


1) Pasqual, Quincy , Robert and Sheridan had a total of 242 muffins. Each of them would have an equal number of muffins if Pasqual bought 10 more muffins, Quincy gave away 21 muffins, Robert increased the number of muffins he had by 2/3 and Sheridan decreased the number of muffins he had by 20%. How many muffins did each of them have ?

2) 0.6 of Luqman's allowance is twice as much as 10% of Zachary's allowance. After Luqman's spends thrice as much as Zachary, Luqman's and Zachary left with $36 and $252 respectively. How much does Zachary and Luqman's each have at first?

Thank you.

Can someone please help me with the above two questions? Thank you !

Both questions could be solved quite easily with MD, I shall use the units approach due to time constraint.

Q1.
In the end, each will have 20u
At first,
P --> 20u -10
Q --> 20u + 21
R --> 12u
S --> 25u
Total --> 77u + 11 = 242
1u --> 33

At first, number of muffins each had :
P --> 650
Q --> 681
R --> 396
S --> 825

cheers.

Hi MathIzzzFun

Can you explain to me how you get the 20u ? Thanks !

[anneshirleygilbert]

Can somebody please help me with this question?


Alan bought 1.5 times as many pencil cases as pens and spent $300 altogether. He spent $60 more on pens than on pencil cases. Given that a pen costs $3.50 more than a pencil case, find the cost of a pencil case.

TIA

[MathIzzzFun]

2DMommy:

MathIzzzFun:

Please help me with these two questions :


1) Pasqual, Quincy , Robert and Sheridan had a total of 242 muffins. Each of them would have an equal number of muffins if Pasqual bought 10 more muffins, Quincy gave away 21 muffins, Robert increased the number of muffins he had by 2/3 and Sheridan decreased the number of muffins he had by 20%. How many muffins did each of them have ?


Thank you.

Can someone please help me with the above two questions? Thank you

Both questions could be solved quite easily with MD, I shall use the units approach due to time constraint.

Q1.
In the end, each will have 20u
At first,
P --> 20u -10
Q --> 20u + 21
R --> 12u
S --> 25u
Total --> 77u + 11 = 242
1u --> 33

At first, number of muffins each had :
P --> 650
Q --> 681
R --> 396
S --> 825

cheers.

Hi MathIzzzFun

Can you explain to me how you get the 20u ? Thanks !

In the end, Robert has 5 blocks (R), and Sheridan has 4 blocks (S). To make them \"equal\", divide into 20 parts ie 4 parts per block for block (R) and 5 parts per block for block (S).

Here's a lengthy with more details than necessary explanation:

http://i46.tinypic.com/2qw3o87.png\">

cheers.

[MathIzzzFun]

anneshirleygilbert:

Can somebody please help me with this question?


Alan bought 1.5 times as many pencil cases as pens and spent $300 altogether. He spent $60 more on pens than on pencil cases. Given that a pen costs $3.50 more than a pencil case, find the cost of a pencil case.

TIA

Please confirm number in blue.

cheers.

[2DMommy]

MathIzzzFun:

2DMommy:

[quote=\"MathIzzzFun\"]Please help me with these two questions :


1) Pasqual, Quincy , Robert and Sheridan had a total of 242 muffins. Each of them would have an equal number of muffins if Pasqual bought 10 more muffins, Quincy gave away 21 muffins, Robert increased the number of muffins he had by 2/3 and Sheridan decreased the number of muffins he had by 20%. How many muffins did each of them have ?


Thank you.

Can someone please help me with the above two questions? Thank you

Both questions could be solved quite easily with MD, I shall use the units approach due to time constraint.

Q1.
In the end, each will have 20u
At first,
P --> 20u -10
Q --> 20u + 21
R --> 12u
S --> 25u
Total --> 77u + 11 = 242
1u --> 33

At first, number of muffins each had :
P --> 650
Q --> 681
R --> 396
S --> 825

cheers.

Hi MathIzzzFun

Can you explain to me how you get the 20u ? Thanks !

In the end, Robert has 5 blocks (R), and Sheridan has 4 blocks (S). To make them \"equal\", divide into 20 parts ie 4 parts per block for block (R) and 5 parts per block for block (S).

Here's a lengthy with more details than necessary explanation:

http://i46.tinypic.com/2qw3o87.png\">

cheers.[/quote]Thank you MathIzzzFun ! :thankyou:

[Neat]

Hi!


Please help!

Alif collected 1400 stamps and 35% of them were Singapore stamps. Fong collected 600 stamps and 55% of them were Singapore stamps. After Alif had given some of his stamps to Fong and Fong had given some of his stamps to Alif, 1/5 of Alif’s stamps and 3/5 of Fong’s stamps were Singapore stamps. How many Singapore stamps did Fong get from Alift?

Thank You.

[speedmaths.012624com]

Neat:

Hi!


Please help!

Alif collected 1400 stamps and 35% of them were Singapore stamps. Fong collected 600 stamps and 55% of them were Singapore stamps. After Alif had given some of his stamps to Fong and Fong had given some of his stamps to Alif, 1/5 of Alif's stamps and 3/5 of Fong's stamps were Singapore stamps. How many Singapore stamps did Fong get from Alift?

Thank You.

Hi,

One possible solution:
Using the Advanced Model Method
(or Bags and Boxes Method)

Alif collected 1400 stamps;
35% (or 490) of them were Singapore stamps
65% (or 910) of them were non-Singapore stamps

Fong collected 600 stamps:
55% (or 330) of them were Singapore stamps
45% (or 270) of them were non-Singapore stamps

Total Singapore stamps → 490 + 330 = 820
Total non-Singapore stamps → 910 + 270 = 1180

After the exchange:
(1/5 of Alif's stamps were Singapore stamps.)
Let Alif put his stamps into 5 Bags
1 Bag of Singapore stamps
4 Bags of non-Singapore stamps

After the exchange:
(3/5 of Fong's stamps were Singapore stamps)
Let Fong put his stamps into 5 Boxes
3 Boxes of Singapore stamps
2 Boxes of non-Singapore stamps

After the exchange:
Singapore stamps: \t\t1 Bag + 3 Boxes → 820
Non-Singapore stamps: \t4 Bags + 2 Boxes → 1180

1 Bag + 3 Boxes → 820
(x 4)
4 Bags + 12 Boxes → 3280\t(Row 1)

4 Bags + 2 Boxes → 1180\t(Row 2)

Row 1 – Row 2
0 Bag + 10 Boxes → 2100

10 Boxes → 2100
1 Box → 210
3 Boxes → 630

After the exchange,
Fong had 630 Singapore stamps
630 – 330 = 300

Fong received 300 Singapore stamps from Alif.

Hope this helps.

Cheers

speedmaths.com

PS.
Parents who wish to know more about the Advanced Model Method can check out our thread in the Happenings forum.

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