Q&A - PSLE Math
-
Hi,
I need help to solve the following question, hope someone can provide detail guide. Thanks in advance.
On a certain day, 10 friends booked 2 badminton courts from 8 am to 11.30am and took turns to play games on them. At any time, only 8 of them played on the 2 badminton courts while the other 2 friends watched. If each of them had the same amount of playtime, how many minutes did each person play on the court? -
Need some pointers on the following questions using units methods
a) There were black and white balls in a bag.
If 20 black balls are removed from the bag, the total number of balls left will be 7 times the number of black balls left.
If 50 white balls are removed from from the bag, the total number of balls left will be 5 times the number of black balls left.
How many balls are there in the bag?
b) Box A contains 350 black balls and 500 white balls.
Box B contains 400 black balls and 100 white balls.
How many black and white balls must be removed from Box B to Box A in order to have 50% of marbles in A are black and 75% of the marbles in B are black.
thanks -
ginginboy:
8am to 11.30am --> 3.5hHi,
I need help to solve the following question, hope someone can provide detail guide. Thanks in advance.
On a certain day, 10 friends booked 2 badminton courts from 8 am to 11.30am and took turns to play games on them. At any time, only 8 of them played on the 2 badminton courts while the other 2 friends watched. If each of them had the same amount of playtime, how many minutes did each person play on the court?
At any time, 8 will play. So,
total available play time --> 8 x 3.5h = 28 h
play time per person --> 28 h/10 = 2.8h = 168 min
cheers. -
ozora:
Need some pointers on the following questions using units methods
a) There were black and white balls in a bag.
If 20 black balls are removed from the bag, the total number of balls left will be 7 times the number of black balls left.
If 50 white balls are removed from from the bag, the total number of balls left will be 5 times the number of black balls left.
How many balls are there in the bag?
thanks
Total number of white balls : black balls --> 6 units : 1 unit + 20
If 50 white balls are removed:
Number of white balls : black balls --> 4 x ( 1 units + 20) : 1 unit + 20
total white balls:
6 units = 4 units + 80 + 50
1 unit --> 65
Total number of balls --> 7 x 65 + 20 = 475
cheers. -
ozora:
similar questions here :Need some pointers on the following questions using units methods
b) Box A contains 350 black balls and 500 white balls.
Box B contains 400 black balls and 100 white balls.
How many black and white balls must be removed from Box B to Box A in order to have 50% of marbles in A are black and 75% of the marbles in B are black.
thanks
- http://www.flickr.com/photos/62167097@N02/7080366811/in/set-72157629537287046
- http://www.flickr.com/photos/62167097@N02/6858744276/in/set-72157629537287046
Total, black balls → 750
Total, white balls → 600
Total, black and white balls → 1350
In the end:
Total, black balls : ½ Box A + ¾ Box B →750
Total, white balls: ½ Box A + ¼ Box B → 600
½ Box B → 750 – 600 = 150
Box B → 300
Box A → 1350 – 300 = 1050
Balls moved from Box B to Box A :
Black balls → 400 – ¾ x 300 = 175
White balls → 100 – ¼ x 300 = 25
cheers. -
MathIzzzFun:
this is definite clearer to understand. I got stuck trying to use the methods provided by the previous examples.
similar questions here :ozora:
Need some pointers on the following questions using units methods
b) Box A contains 350 black balls and 500 white balls.
Box B contains 400 black balls and 100 white balls.
How many black and white balls must be removed from Box B to Box A in order to have 50% of marbles in A are black and 75% of the marbles in B are black.
thanks
- http://www.flickr.com/photos/62167097@N02/7080366811/in/set-72157629537287046
- http://www.flickr.com/photos/62167097@N02/6858744276/in/set-72157629537287046
Total, black balls → 750
Total, white balls → 600
Total, black and white balls → 1350
In the end:
Total, black balls : ½ Box A + ¾ Box B →750
Total, white balls: ½ Box A + ¼ Box B → 600
½ Box B → 750 – 600 = 150
Box B → 300
Box A → 1350 – 300 = 1050
Balls moved from Box B to Box A :
Black balls → 400 – ¾ x 300 = 175
White balls → 100 – ¼ x 300 = 25
cheers.
after trf:
Black : white
Box A -> 1triangle: 1 triangle
Box B-> 3 diamonds: 1 diamond.
I do not know how to equate and divide by how many. so how do i go about doing that
as for Q1: i got it and redraw it as below.![](\"http://i50.tinypic.com/tagcg7.jpg\")
http://i50.tinypic.com/tagcg7.jpg\">
-
ozora:
Using units and parts :
this is definite clearer to understand. I got stuck trying to use the methods provided by the previous examples.MathIzzzFun:
Need some pointers on the following questions using units methods
b) Box A contains 350 black balls and 500 white balls.
Box B contains 400 black balls and 100 white balls.
How many black and white balls must be removed from Box B to Box A in order to have 50% of marbles in A are black and 75% of the marbles in B are black.
similar questions here :
- http://www.flickr.com/photos/62167097@N02/7080366811/in/set-72157629537287046
- http://www.flickr.com/photos/62167097@N02/6858744276/in/set-72157629537287046
Total, black balls → 750
Total, white balls → 600
Total, black and white balls → 1350
In the end:
Total, black balls : ½ Box A + ¾ Box B →750
Total, white balls: ½ Box A + ¼ Box B → 600
½ Box B → 750 – 600 = 150
Box B → 300
Box A → 1350 – 300 = 1050
Balls moved from Box B to Box A :
Black balls → 400 – ¾ x 300 = 175
White balls → 100 – ¼ x 300 = 25
cheers.
after trf:
Black : white
Box A -> 1triangle: 1 triangle
Box B-> 3 diamonds: 1 diamond.
I do not know how to equate and divide by how many. so how do i go about doing that
as for Q1: i got it and redraw it as below.
Total, black balls → 750
Total, white balls → 600
Total, black and white balls → 1350
IN the end,
Black balls : White Balls, in Box A --> 1u : 1u (1 triangle : 1 triangle)
Black balls : White Balls, in Box B --> 3p : 1p (3 diamonds : 1 diamond)
Total black balls: 1u + 3p = 750
Total white balls: 1u +1p = 600
So, 2p --> 750 - 600 = 150
1p --> 75
1u --> 600 - 75 = 525
Number of balls moved from B to A:
Black --> 400 - 3 x 75 = 175
White --> 100 - 75 = 25
cheers. -
ozora:
The units approach was used in the posted solution as this method could be understood by P4 students. The solution can be directly translated into a MD solution replacing the units with model blocks.
as for Q1: i got it and redraw it as below.
Here's a solution using the units-parts or UP approach:![](\"http://i48.tinypic.com/3148efb.png\")
cheers. -
MathIzzzFun:
great thanks to u.
The units approach was used in the posted solution as this method could be understood by P4 students. The solution can be directly translated into a MD solution replacing the units with model blocks.ozora:
as for Q1: i got it and redraw it as below.
Here's a solution using the units-parts or UP approach:
cheers. -
Need some guide again in the following question.
John had some money. He spent it all in 3 stores. In each store, he spent $2 more than half of what he had when he entered.
a(how much did he spend at the last store?
b)how much did he have at first
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login