Q&A - PSLE Math

[Winx5015]

Q1). At 6 am, a car left Town A for Town B at a speed of 65km/h. At the same time, another car left Town B for Town A at a speed of 55km/h. The distance between the two towns was 720km. At what time did the 2 vehicles pass each other?


Q2). A shopkeeper had some markers in red and blue. If 50 red markers and 25 blue markers were sold each week, there would be 500 red markers left when all the blue markers were sold. If 25 red markers and 50 blue markers were sold each week, there would be 800 red markers left when all the blue markers were sold. How many markers did the shopkeeper have at first?

Q3). A rectangular tank measuring 40cm by 30cm by 40cm was 1/6 filled with water. At 0930h, Tap X with water flowing out at a rate of 3 litre per minute was turned on. At 0932h, Tap Y was turned on to drained water out of the tank at a fixed rate. At 0943h, the tank was 75% filled with water. At what time would the tank be filled to the brim?

Thanks

[MathIzzzFun]

Winx5015:

Q1). At 6 am, a car left Town A for Town B at a speed of 65km/h. At the same time, another car left Town B for Town A at a speed of 55km/h. The distance between the two towns was 720km. At what time did the 2 vehicles pass each other?


Thanks

Hi

Time taken to meet = 720 / (55+65) h = 6h
6am + 6h --> 12.00pm
They will meet at 12.00pm


http://tinyurl.com/mathizzzfun-speed-notes01

cheers.

[MathIzzzFun]

Winx5015:

Q2). A shopkeeper had some markers in red and blue. If 50 red markers and 25 blue markers were sold each week, there would be 500 red markers left when all the blue markers were sold. If 25 red markers and 50 blue markers were sold each week, there would be 800 red markers left when all the blue markers were sold. How many markers did the shopkeeper have at first?

Thanks

Hi

Case 1:
Markers sold, Red : Blue --> 50 : 25 = 2 : 1 --> 4u : 2u (*using 2u for Blue because all the blue markers were sold in both cases)
Total number of red markers --> 4u + 500
Total number of markers --> 6u + 500
Case 2:
Markers sold, Red : Blue --> 25 : 50 = 1 : 2 --> 1u : 2u
Total number of red markers --> 1u + 800

Number of red markers are the same in both cases:
4u + 500 = 1u + 800
1u --> 100
Total number of markers --> 6 x 100 + 500= 1100

cheers.

[tianzhu]

Winx5015:

Q1)

Q3). A rectangular tank measuring 40cm by 30cm by 40cm was 1/6 filled with water. At 0930h, Tap X with water flowing out at a rate of 3 litre per minute was turned on. At 0932h, Tap Y was turned on to drained water out of the tank at a fixed rate. At 0943h, the tank was 75% filled with water. At what time would the tank be filled to the brim?

Thanks

Hi

Good Morning.

Not much time to prepare the slide, so I’ll go with some pointers.

Volume of tank ------- 48 litres

Volume of water in tank ------- 8 litres (1/6)

At 0932h , water in tank ------- 8 + (3*2) ------- 14 litres

From 0932h to 0943h, water flowing from tap X ----- 11*3 ------ 33 litres
14 + 33 ------- 47 litres

But the tank was 75% filled with water, so water had been drained out due to tap Y .

75% of 48 litres ------ 36 litres

47 – 36 ------- 11

11/11 ------ 1, hence water drain out rate from tap Y is 1 litre/minute.

From 36 litres to 48 litres, remember tap X adds 3 litres/min and tap Y drains 1 litres/min, so the net flow of water into tank is 2 litres/min.

12/2 ------- 6 minutes

From 0943h add 6 minutes, we’ll have 0949h

Best wishes

[Essential]

Good afternoon Tianzhu, need your kind help for this question.

Eugene, Freddy and George had some playing cards. Freddy had 200 more playing cards than Eugene. George had 3/4 the number of cards Freddy had. After George lost 1/6 of his cards to Eugene, he had 320 fewer cards than Eugene. What was the ratio of the number of cards Eugene had to the number of cards Freddy had to the number of cards George had in the end?

[tianzhu]

Essential:

Good afternoon Tianzhu, need your kind help for this question.

Eugene, Freddy and George had some playing cards. Freddy had 200 more playing cards than Eugene. George had 3/4 the number of cards Freddy had. After George lost 1/6 of his cards to Eugene, he had 320 fewer cards than Eugene. What was the ratio of the number of cards Eugene had to the number of cards Freddy had to the number of cards George had in the end?

Hi

Good Afternoon.

You may use MD or work with units.

Consider this at the start.

Eugene ------ 8 units
Freddy ------ 8 units + 200
George ------ 6 units + 150

In the end

Eugene ------ 9 units + 25 ------ 970
Freddy ------ 8 units + 200 ------ 1040
George ------ 5 units + 125 ------ 650

9 units + 25 ------- 5 units + 125 +320

1 unit ------- 105

The ratio ------- 970:1040:650 ----- 97:104:65

Best wishes

[Winx5015]

:thankyou:


MathIzzzFun and tianzhu for your help in solving my questions.

Have a nice day

[Winx5015]

Hi, need help for the following questions.


Q1). Mr Lee sold 15% of his cupcakes on Monday. He sold 90 fewer cupcakes on Tuesday than on Monday. He then sold 70 fewer cupcakes on Wednesday than on Tuesday. On Thursday, he sold 330 cupcakes and found that he had half of his original number of cupcakes left. How many cupcakes did he sell altogether?

[Winx5015]

http://i48.tinypic.com/t6qe6e.jpg\">

[Michaelia0816]

MathIzzzFun:

kiasuaunt:

Hi.


Q1.
Mr Lee sold 15% of his cupcakes on Monday.
He sold 90 fewer cupcakes on Tuesday than on Monday.
He then sold 70 fewer cupcakes on Wednesday than on Tuesday.
On Thursday,he sold 330 cupcakes and found that he had half of his original number of cupcakes left.
How many cupcakes did he sell altogether?



Hi

for Q1, you may want to start with :
Total number of cakes = 100u and then work through the question to the end and equating the remainder to 50u

I will start with Mon & Tue, and hopefully you can complete the rest...

Total --> 100u

Mon-- Sold 15u, Left 85u
Tue -- Sold 15u-90, Left 70u+90

cheers.

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