Q&A - PSLE Math

[MathIzzzFun]

ozora:

Need guide n help on the following questions.

q1. I had some red and blue stickers. If 72 red stickers were removed, the ratio of the number of red stickers to blue stickers would be 1:2. If 180 blue stickers were removed, the ratio of the number of red stickers to blue stickers would be 5:1. How many red stickers were there at first?

q2.There were 2 identical flights of steps.For the 1st flight of steps , Samuel walked up some steps and ran 7 steps in 67seconds. For the 2nd flight of steps, Samuel walked up some steps and ran 15 steps in 43seconds. How long will Samuel take to walk up both flight of steps?

q3) 2 candles, S and T have different lenght and thickeness. Candle S can burn for 8 hours while Candle T can burn for 4 hours. Both candles are lighted at the same time. After 2 hours, they had the same length left. Find the ratio of the initial length of Candle S to initial length of Candle T .

Hi

Q2. For 1st flight of steps, Samuel walked 8 more steps instead of running, and the extra time from walking 8 steps = 67s - 43s = 24s
Extra time from walking 1 step instead of running = 24/8 = 3s

So, if he were to walk the entire flight of steps (1st flight of steps), extra time taken = 7 x 3 = 21s

total time taken to walk the entire flight of steps = 67s + 21s = 88s

cheers.

[MathIzzzFun]

ozora:

Need guide n help on the following questions.

q1. I had some red and blue stickers. If 72 red stickers were removed, the ratio of the number of red stickers to blue stickers would be 1:2. If 180 blue stickers were removed, the ratio of the number of red stickers to blue stickers would be 5:1. How many red stickers were there at first?

q2.There were 2 identical flights of steps.For the 1st flight of steps , Samuel walked up some steps and ran 7 steps in 67seconds. For the 2nd flight of steps, Samuel walked up some steps and ran 15 steps in 43seconds. How long will Samuel take to walk up both flight of steps?

q3) 2 candles, S and T have different lenght and thickeness. Candle S can burn for 8 hours while Candle T can burn for 4 hours. Both candles are lighted at the same time. After 2 hours, they had the same length left. Find the ratio of the initial length of Candle S to initial length of Candle T .

Hi

Q1. Ratio of Red stickers : Blue Stickers, after removing 72 Red stickers
= 1u : 2u

If 180 Blue stickers are removed, 1u + 72 : 2u -180 = 5: 1

So, 1u + 72 = 5 x (2u-180) = 10u - 900
9u = 972, 1u = 108

Initial number of red stickers = 1u + 72 = 108 + 72 = 180

cheers.

[bobsg01]

Ratio problem.


Thanking in advance for help.

http://i55.tinypic.com/wjued3.jpg\">

[Nebbermind]

MathIzzzFun:

stary:

Hi all,


Have a question here...

73A x B = 4428
What is the value of A + B? :?:

Hi

A=8, B = 6, A+B = 14

cheers.

I still donch get it!! :?

[dovetail]

MathIzzzFun:

stary:

Hi all,


Have a question here...

73A x B = 4428
What is the value of A + B? :?:

Hi

A=8, B = 6, A+B = 14

cheers.

If A=8 and B=6

Then, 73A X B = 73x8 x 6= 3504, not 4428.

I think there is something wrong with the question.

AB = 4428/73 = 60 and 48/73

IF A and B need not be integers, There are many possible pairs of answers.

Say, you choose the easiest, A=1 and B=4428/73 or A=2 and B=2214/73,
etc, etc..

So A+B can be 1+60and48/73 = 61and48/73

Many other answers, I think this question needs to be tighten with more criteria.

What do you think.

BTW, bobsg01, You are very much welcome.

[MathIzzzFun]

Nebbermind:

MathIzzzFun:

[quote=\"stary\"]Hi all,


Have a question here...

73A x B = 4428
What is the value of A + B? :?:

Hi

A=8, B = 6, A+B = 14

cheers.

I still donch get it!! :?[/quote]Hi

I believe the question is supposed to be

73A
x B
-------
4428
-------

cheers.

[Nebbermind]

OK, now that makes sense!!

[MathIzzzFun]

dovetail:

MathIzzzFun:

[quote=\"stary\"]Hi all,


Have a question here...

73A x B = 4428
What is the value of A + B? :?:

Hi

A=8, B = 6, A+B = 14

cheers.

If A=8 and B=6

Then, 73A X B = 73x8 x 6= 3504, not 4428.

I think there is something wrong with the question.

AB = 4428/73 = 60 and 48/73

IF A and B need not be integers, There are many possible pairs of answers.

Say, you choose the easiest, A=1 and B=4428/73 or A=2 and B=2214/73,
etc, etc..

So A+B can be 1+60and48/73 = 61and48/73

Many other answers, I think this question needs to be tighten with more criteria.

What do you think.

BTW, bobsg01, You are very much welcome.[/quote]hi

I assumed that this is a primary school's question and therefore it is very likely to be in the form

73A
x B
------
4428
------



cheers.

[Nebbermind]

bobsg01:

Ratio problem.


Thanking in advance for help.

http://i55.tinypic.com/wjued3.jpg\">

Hi bobsg01

Think it wld be good if u try to work on your modelling otherwise these qns will be a pain!!

For this qn, it's impt to see the relationship between the 60% left in Y and the 6 units (7:6 final ratio). Once u draw the model, and move the units back-forth, u shd get the answers.

[stary]

Thanks people fo the suggested answers...