SOS mum:

Hi, ps help. Many tks and God Bless:)



2) I think of a two-digit number. The sum of the digits is 13. When I reverse the digits of the number, I get another number whose value is 9 more than the first number. What is the number I thought of? (Must use simultaneous Linear Equations)

Hi,

Let the two-digit number be X Y (note this is not X multiply Y).

Condition 1: The sum of the digits is 13

Thus,

X + Y = 13 --------------------------eqn 1

Condition 2: When I reverse the digits of the number, I get another number whose value is 9 more than the first number, that is Y X - X Y = 9

Thus,\t

Y X - X Y = 9
(10 Y + X) - (10X + Y) = 9
10 (Y - X) - (Y - X) = 9
Y - X = 1 ----------------------------eqn 2

[Note: a two-digit number, for example 76 can also be written as 76 = (10 x 7) + 6]

With eqn 1 and 2, we can solve for X and Y. The two-digit number X Y can therefore be determined.

Regards

Prudence99:

Hi,


Here is a question which I also have the steps to solving the problem but I need clarification on one step. Kindly assist.

Mrs Lee made some cookies and packed them in 50 small boxes and 12 big boxes that had an equal number of cookies each. Each big box had 30 more cookies than each small box. 5/8 of the cookies made were packed in small boxes.
(a) Mrs Lee collected $559.90 after selling all the small boxes of cookies at $8.55 each and some big boxes of cookies at $16.50 each. How many big boxes of cookies were left?
(b) How many cookies did Mrs Lee make?

So the steps to solving (b) is as follows:

Big Small Total
3 5 8
(x10) 30 50 80

12 big boxes = 12u + (30x12)
30u = 12u + 360
18u = 360
1u = 20

Total cookies made = 80u x 20
= 1,600

Question: why do we multiply the original ratio by 10?

Many thanks in advance!

Hi,

If you considered the original ratio,

no. of cookies in one small box = 5U/50 = 0.1U



Now, if you multiply the original ratio by 10, then

no. of cookies in one small box = 50U/50 - 1U



From the subsequent workings, you could see that it is easier to work with a whole no. (in this case 1) then working with a decimal or fraction (in this case 0.1 or 1/10). Thus reducing careless mistakes in computing.

You could also multiply it with 100 but we do not want to work with a large no. either.

So long that you are comfortable and confident, be it whole no., decimal or fraction, all of them will give the same answer.

Regards

Sruthi:

http://i62.tinypic.com/zk1v2g.jpg\"> - please help me with this question

Hi,

You may have noted that

(1) this is a \"double if\" or 2 scenario question
(2) the total sum remained the same

First Scenario

You already established that the ratio of

Tony : Alan : Total
10 : 2 : 12

Second Scenario

The key lies in understanding/interpreting the statement \"....40% more than...\"

In this case, the ratio of

Tony : Alan : Total
100 : 140 : 240
5 : 7 : 12


From (2), the Total is now the same, i.e. 12.

So, can you see that,

5U --> 300
10U --> 600

Regards

Sruthi:

http://i57.tinypic.com/a4x18p.jpg\"> . I need help to solve this problem .


Please help .

Thanks a lot ..

Hi,

I will just continue from where you have stopped.

http://i60.tinypic.com/10sdglv.jpg\">

Regards

acehkr3009:

Oldschool:

[quote=\"acehkr3009\"]Hi all,


Will need help on finding the area of the unshaded triangle.

Thanks.

http://i59.tinypic.com/wwhfl5.jpg\">

Hi,

Can you find the area of triangle from here?

http://i61.tinypic.com/2hx3g49.jpg\">

Regards

Hi,

Thanks for the reply.

The triangles are not stated as right angle triangle.
Is it possible to have isosceles triangles inside this quadrant that may not be right angle?
If so, then not too sure how to find area of the triangles....please advise...thks[/quote]
Hi,

Yes, it is possible to have iso. triangle inside the quadrant that is not a right angle triangle.

So, you have a valid point here. If the iso. triangle is not a rt. angle triangle (since it is stated that is not drawn to scale) them there would be infinite answers.

Regards

acehkr3009:

Hi all,


Will need help on finding the area of the unshaded triangle.

Thanks.

http://i59.tinypic.com/wwhfl5.jpg\">

Hi,

Can you find the area of triangle from here?

http://i61.tinypic.com/2hx3g49.jpg\">

Regards

cftan:

tianzhu:

[quote=\"bookwormkids\"]
2)
Catherine has a box containing some black and white counters. When she adds in 15 white counters, 65% of the counters in the box are black. If she adds in another 40 black counters, 75% of the counters in the box are black. How many white counters are there in the box at first?

I used the following approach but could not arrive to the same answer.

Black :White
13u:7u-15
0:+15
13u:7u

Black :white
13u:7u-15
+40:0
3p:1p

13u+40=3p
7u-15=1p

13u+40=3(7u-15)
8u=85

Can someone advise what went wrong? Thanks.[/quote]
Hi,

The 2nd event is a continuous from the first event.

So, it should be, instead

Black : White
13U : 7U
+40 : 0
3P : 1P

....

Regards

yeyewynes:

yeyewynes:

please help to solve this problem:


Shannon and Tammy had a total of 709 beads.
After Shannon bought another 74 beads and Tammy gave away 1/5 of her beads, both of them had the same number of beads left.
Find the number of beads Shannon had at first.

Looking forward on your replies...

can solve this using Algebra ... prob is how to explain to P5 student.

Hi,

You can try using MD.

http://i59.tinypic.com/ehhq49.jpg\">

Regards

Er Jie:

Hi, I have a query:


The temperature of a cup of hot coffee was 70°C at 11.58a.m. Its temperature dropped by 3.5°C per minute. Its final temperature was 60% lower than the original temperature. At what time was the temperature 60% lower than the original temperature?

Answer provided by assessment book:
60% of 70°C = 60/100 x 70 = 42°C
Difference -> 70 – 42 = 28°C
3.5°C -> 1 min
28°C -> 8 min

11.58a.m. -> 12. 06p.m.
The temperature was 60% lower than the original temperature at 12.06p.m.

How do you interpret 60% lower than the original temperature?
Should the final temperature be 40% of 70°C = 28°C
or 60% of 70°C = 42°C ?

TIA.

Hi,

You might want to take a look at this post from CIMMAN,

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=1000542#p1000542


Regards

chloecube:

Hi,


i got problem understanding this statement

\" Ravi has 1.5 times more marble than May\"
what does 1.5 times mean and how do i draw the model ?
thks

Hi,

You might want to take a look at this post from CIMMAN,

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=1000542#p1000542

Regards