Q&A - P5 Math

[MathIzzzFun]

buds:

Helloooo again, tianzhu! :peekaboo:


I have a few more for you here.

I am thinking of a fraction.
The sum of its numerator and denominator is 20.
When i add 22 to its denominator, the fraction becomes 1/6.
What is the fraction i am thinking of?

This question carries 4 marks! :yikes:

Benjamin left Singapore for an 8-day exchange programme in Perth.
When he returned, he realized he had to tear off 8 pages from his day to day calendar.
The sum of all the dates on the pages he tore is 84.
On which day did he leave Singapore?

1. 5 February
2. 6 January
3. 7 June
4. 8 August

This wan 2 marks.

I suppose the task at hand is more to the issue of solving such questions
without having to spend too much time on them. When have to
think too long & too much over a few questions my DD1 gets her
usual what she calls mental block.. head jammed.. cannot think.. :slapshead:

Hi

these are familiar questions phrased in another way. Compare these to the following :

1) Nino (numerator) and Dominic (denominator) had a total of 20 stickers. If Dominic were to collect another 22 stickers, Nino will have 1/6 as many stickers as Dominic. How many stickers did each of them have ?

2) Benjamin was reading a book. He decided that he would read one more page than the previous day. If Benjamin read a total of 84 pages over 8 days, how many pages did he read on Day 1 ?

http://i42.tinypic.com/35mo390.jpg\">

cheers.

[mathnoobs]

KSgal:

chokos:

Hi all,

Thanks for helping.
I need help to solve the following questions:

Q 1) Some pupils from 5K, 5L and 5M took part in a Social Studies quiz. 34 participants were from 5L and 5M. 21 participants were not from 5L and 19 participants were not from 5M. How many pupils from these 3 classes took part in the quiz? Model Answer: 37pupils

5L + 5M: 34

21 not from 5L means that the 21 are from 5K + 5M

19 not from 5M means that the 19 are from 5K + 5L

Notice that if you add all the numbers up, you will get 2 5K, 2 5L and 2 5M.

So:

2 5K, 2 5L, 2 5M--34+21+19=74
No. of pupils from all 3 classes (1 5K, 1 5L, 1 5M)--74/2=37

Ans: 37 pupils

Hope this helps ^_^

I'm afraid I'm totally lost here. I only got up to this stage:
http://i41.tinypic.com/2v1upf4.png\">

maybe you can help to fill up the diagram. I don't understand where the 2 5K comes from, or the 2 5L...

[chokos]

Hi,

Manage to get the solution for Q4,pls let me know if there is a faster way to do it.

Solution:
----------
If Jason and Keven spent $100 and $50 each day respectively,
Equation 1
------------
J - (100 * number of days) = 1300
K - (50 * number of days) = 0

If Jason and Kevin spent $50 and $100 each day respectively,
Equation 2
------------
K - (100 * number of days * 1/2 )= 0
(inorder to get $0, the days have to be shorter by ½ as he spent twice the amount)
J - (50 * number of days * 1/2 ) = 3700
Therefore,
J – ( 25 * number of days) = 3700

Compare with Equation 1
----------------------------
J - (100 * number of days) = 1300
75 * number of days = 2400
Number of days = 2400 / 75 = 32
J = 1300 + 100 * 32 = $4500

[cimman]

buds:

I am thinking of a fraction.
The sum of its numerator and denominator is 20.
When i add 22 to its denominator, the fraction becomes 1/6.
What is the fraction i am thinking of?

I've recently developed a way to solve problem sums with algebra and simultaneous equations. It offers a simple way of forming the necessary equations. For the above problem, it is an equation with one unknown.
http://i40.tinypic.com/3347uxs.png\">
The fonts in black are values transferred directly from the problem to the table. The fonts in red are calculated values.
The calculation is based on this basic formula: Before + Transfer = After
how did I get (6 units - 22) for Denominator (Before) ?
it is from Before = After - Transfer
= 6 units - (+22)
= 6 units - 22
Since there was no mention of any changes to the Numerator, we put a 0 in the Transfer box for numerator.

The red circle simply circles the relevant equation.
All equations are dervied directly from the table.

If you're open to algebra and simultaneous equations, this method can solve complex problems easily, ie. the equations can be formed easily through the table alone. From the table, the relationships can be clearly seen without a deep comprehension of the problem sum and the relationships of the data values.
The relationships are derived from the table instead of from the problem sum.

[YumYum]

Hi, Can someone pls help with this question:


Farmer Tan has ducks and cows on his farm. The total number of ducks and cows is between 20 and 40. The ratio of the total number of ducks’ legs to the total number of cows’ legs is 5:9. What is the total number of ducks and cows on the farm?

Thanks

[tianzhu]

YumYum:

Hi, Can someone pls help with this question:


Farmer Tan has ducks and cows on his farm. The total number of ducks and cows is between 20 and 40. The ratio of the total number of ducks' legs to the total number of cows' legs is 5:9. What is the total number of ducks and cows on the farm?

Thanks

Hi

One needs to differentiate the ratios representing the number of legs and the number of animals. The ratios for the number of legs and the number of animals are of different measures.

The total number of ducks' legs to the total number of cows' legs is 5:9 ------ 20:36 (equivalent ratios)

A duck ----- 2 legs, a cow ----- 4 legs

This means the total number of ducks to the total number of cows ----- 10:9 -----20:18

Ducks ----- 20
Cows ----- 18

There are 38 ducks and cows.

Best wishes

[ariasnow]

Need help on this question.



Ali’s salary was 5/6 of Teri’s salary. After Ali and Teri each spent $1080, Ali then had 7/9 as much as money as Teri. How much was their combined income?

thanks.

[ariasnow]

Another question:


Sam had 20 more cards than Tony. During a game, Tony lost 14 of his cards to Sam. In the end, Sam had 4 times the number of cards that Tony had. How many cards did Sam have at first?

[tianzhu]

ariasnow:

Need help on this question.



Ali's salary was 5/6 of Teri's salary. After Ali and Teri each spent $1080, Ali then had 7/9 as much as money as Teri. How much was their combined income?

thanks.

Hi

Since Ali and Teri spent the same amount of money(1080), the difference in their salary did not change.

At first

Ali:Teri -----5:6 (Difference – 1) ------ 10:12 ((Difference – 2)

In the end

Ali:Teri -----7:9 (Difference – 2)

Make the difference in units the same.

3 units ------ 1080
1 unit ------ 360

Combined salary ------ 22*360 ------- 7920

Best wishes

[ariasnow]

Another question.


Tom was reading a book. He read 1/8 of it on the first day, 1/5 of it on the 2nd day and 1/4 of it on the 3rd day. After that, he still had 68 pages to read. How many pages does the book have?