Q&A - PSLE Math

[2DMommy]

MathIzzzFun:

2DMommy:

Please help me with these two questions :



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 !

3/5 Luq's allowance = 2/10 Zac's allowance
3/5 Luq's allowance = 3/15 Zac's allowance
Luq's allowance : Zac's allowance --> 1 : 3

Luq's spending : Zac's spending --> 3u : 1u
Luq's allowance : Zac's allowance --> 3u + $36 : 1u + $252 = 1 : 3

So, 9u + $108 = 1u + $252
1u --> 18

Luq's allowance --> $90
Zac's allowance --> $270

cheers.

Thank you MathIzzzFun

[Chan09]

Is there a faster method to solve this?

Eveyday A gets 10 additional new cards. On every third day he gives 3 cards away. If A starts with 8 cards on the first day, on which day will he have exactly 180 cards?

Thank you.

[oosh]

Hi


Would greatly appreciate some help on this question:

Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

:thankyou:

[Michaelia0816]

Hi oosh,


A+B---> 4 days
[B]+C---> 1.5 days
[A]+C---> 1.5 days*2= 3 days

Let see,
A took 1.5 days more than B.
B---> (4-1.5)/2=1.125 days to complete
A---> 1.125+1.5=2.625 days to complete
C--->3-2.625=0.375 days to complete
B+A+C---> 4.125 days
4.125 days~ 4 days ( as it is on the 4 days)

[kiasuaunt]

speedmaths.com:

kiasuaunt:

Hi - pls help me with the md for this q:


Ben n Mary went shopping with a total of $204. Ben had $12 more than Mary. Mary spent 4 times as much money as Ben and was left with half the amount of money that Ben had left.

a) How much money did Ben bring along for shopping?

b) How much money had Ben left after shopping?

Thank you.

Hi,

One possible Solution to Part (b)
Using the Advanced Model Method
(or Bags and Boxes Method)

Sam → ($204 + $12) ÷ 2 = $108
Mary → ($204 - $12) ÷ 2 = $96

Let Sam put his $108 into 1 Bag and 2 Boxes.
Let Mary put her $96 into 4 Bags and 1 Box.

(Each of the 5 Bags contains the same amount of money.)
(Each of the 3 Boxes contains the same amount of money.)

Mary spent 4 times as much money as Ben.
Mary spent her 4 Bags of money, and Ben spent his 1 Bag of money.

Mary was left with half the amount of money that Ben had left.
Mary had 1 Box of money left, and Ben had 2 Boxes of money left.

Mary:
$96 → 4 Bags + 1 Box…………….(Row 1)

Sam:
$108 → 1 Bag + 2 Boxes
(x 4)
$432 → 4 Bags + 8 Boxes…………(Row 2)

Row 2 – Row 1
$432 - $96 → $336 → 0 Bag + 7 Boxes
7 Boxes → $336
1 Box → $48
2 Boxes → $96

Ben had 2 Boxes of money left.
Ben had $96 left.

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.

.

:thankyou: very much for your clear explanations - also your time n effort typing out the ans. - appreciate it very much.

[MathIzzzFun]

oosh:

Hi


Would greatly appreciate some help on this question:

Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

:thankyou:

Work needed to complete job --> 12 units
A+B --> 4 days --> 3 units/day
B+C --> 1.5 x 4 days = 6 days --> 2 units/day
A+C --> 12 days --> 1 unit/day

Adding...
2 x (A+B+C) --> 6 units/day
(A+B+C) --> 3 units /day
12 units ---> 12/3 = 4 days

A,B and C will take 4 days to complete the job.

cheers.

[oosh]

Michaelia0816:

Hi oosh,


A+B---> 4 days
[B]+C---> 1.5 days
[A]+C---> 1.5 days*2= 3 days

Let see,
A took 1.5 days more than B.
B---> (4-1.5)/2=1.125 days to complete
A---> 1.125+1.5=2.625 days to complete
C--->3-2.625=0.375 days to complete
B+A+C---> 4.125 days
4.125 days~ 4 days ( as it is on the 4 days)

Hi Michaelia, thanks do much for your help but I'm a bit confused coz you mentioned that B + C = 1.5days but the question said that they took 1 1/2 times as many days to complete the job...


Thanks for any assistance.

[oosh]

MathIzzzFun:

oosh:

Hi


Would greatly appreciate some help on this question:

Abel and Ben can build a model aircraft together in 4 days. Ben and Calvin can do the same job together in 1 1/2 times as many days. Abel and Calvin can complete the same job together in twice the number of days Ben and Calvin can do together. If the three boys decide to work together, how long will they take to complete their job?
(Answer: 4 Days)

:thankyou:

Work needed to complete job --> 12 units
A+B --> 4 days --> 3 units/day
B+C --> 1.5 x 4 days = 6 days --> 2 units/day
A+C --> 12 days --> 1 unit/day

Adding...
2 x (A+B+C) --> 6 units/day
(A+B+C) --> 3 units /day
12 units ---> 12/3 = 4 days

A,B and C will take 4 days to complete the job.

cheers.

Hi, thanks so much for your explanation. I can understand this better.

[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.

[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