Q&A - PSLE Math

[fightingmom]

Hi,


Please help with the following question :

At 7am, Car A left Town X for Town Y while Car B left Town Y for Town X. At 3pm, the two cars passed each other. 5 hours later, Car A reached Town Y but Car B was still 150km away from Town X. Find the distance between Town X and Town Y.

TIA!

[MathIzzzFun]

mumworks:

Thanks Speedmaths.com and MathIzzzFun for helping to answer my earlier questions.


Can anyone help on this Qs ?

1/2 of a rectangle overlaps with 1/3 of a circle. What fraction of the figure is overlapped ?

Thank you very much.

1/2 rectangle = 1/3 circle
rectangle --> 2 units
circle --> 3 units
overlapped --> 1 unit

can you continue from here ?

cheers.

[jarenchuatw]

Got another question to to ask - see attached, but ignore the writing in blue (coz I m not sure whether it is correct or not)

[MathIzzzFun]

fightingmom:

Hi,


Please help with the following question :

At 7am, Car A left Town X for Town Y while Car B left Town Y for Town X. At 3pm, the two cars passed each other. 5 hours later, Car A reached Town Y but Car B was still 150km away from Town X. Find the distance between Town X and Town Y.

TIA!

concept of combined speed

When Car A and Car B meet, the total distance covered is XY and the total time taken is 8 hours (7am to 3pm).

5 hours after passing each other, remaining distance to be covered = 150 km

Both cars took 3 hours (8-5) to cover a total distance of 150 km,
combined speed --> 150 km/3h = 50km/h (quite a slow speed considering that this is a combined speed)
Total distance between XY = 50 km/h x 8h = 400 km

cheers.

[MathIzzzFun]

Chan09:

Need help on these; thank you


2) There are 98 teachers and each female teacher has 8 notepads and each male teacher has 3 notepads given to them. The male teachers received 355 notepads less than the female teachers. How many female teachers are there?
Ans: 59, for this question I applied the excess and shortage concept though I understand that this is incorrect as it is suppose to make a supposition. Plse help.

similar questions using area model --> which is supposition method using MD

http://www.flickr.com/photos/62167097@N02/6963704884/in/set-72157629901522689/

http://www.flickr.com/photos/62167097@N02/6808896113/in/set-72157629901522689

http://www.flickr.com/photos/62167097@N02/6879749576/in/photostream

http://www.flickr.com/photos/62167097@N02/7634466300/in/set-72157629901522689



cheers.

[MathIzzzFun]

Chan09:

Need help on these; thank you


1) team A and team B sent pupils in groups of 10, for a ball game. If the 2 teams used mini vans that have a seating capacity of 14 passengers, they will need 72 vans. If they use mini vans that have a seating capacity of 19, team B will need 7 more vans than team A. If the 2 teams do not share a van and each van is pack to a max of 19 for team B, how many more pupils are there in team B than team A?
Ans: 140

I will provide some pointers for Q1

Total number of pupils is a multiple of 10 since both teams sent pupils in groups of 10.
So, 72 vans with seating capacity of 14 passengers --> what is the total number if all vans are full ? What is the number of pupils ?

Once the number of pupils is determined, how many vans with seating capacity of 19 is needed to accomodate all ?

cheers.

[fightingmom]

MathIzzzFun:

fightingmom:

Hi,


Please help with the following question :

At 7am, Car A left Town X for Town Y while Car B left Town Y for Town X. At 3pm, the two cars passed each other. 5 hours later, Car A reached Town Y but Car B was still 150km away from Town X. Find the distance between Town X and Town Y.

TIA!

concept of combined speed

When Car A and Car B meet, the total distance covered is XY and the total time taken is 8 hours (7am to 3pm).

5 hours after passing each other, remaining distance to be covered = 150 km

Both cars took 3 hours (8-5) to cover a total distance of 150 km,
combined speed --> 150 km/3h = 50km/h (quite a slow speed considering that this is a combined speed)
Total distance between XY = 50 km/h x 8h = 400 km

cheers.

This is the first time I came across \"combined speed\".

:thankyou: so much for your help ! :salute:

[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.

[speedmaths.012624com]

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 (a)

Ben n Mary went shopping with a total of $204
Sum = $204

Ben had $12 more than Mary
Difference = $12

Bigger number = (Sum + Difference) ÷ 2
Sam → ($204 + $12) ÷ 2 = $108

Hope this helps.

Cheers

speedmaths.com


PS:
Smaller number = (Sum - Difference) ÷ 2
Mary → ($204 - $12) ÷ 2 = $96

-

[speedmaths.012624com]

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.

.