Q&A - P5 Math

[kavisuresh]

Hi,

Pls help to solve .
1.Tins X,Y,Z each contained some chocolate powder. Mr.John transferred 1/8 of the chocolate powder from tin X to tin Y , then scooped 1/8 of the chocolate powder from tinY into tin Z and finally transferred 1/8 of the chocolate powder from tin Z to tin X. Now there are 49g of chocolate powder in each tin. How much chocolate powder was there in each tin at first ?

Thank you.

[jieheng]

kavisuresh:

Hi,

Pls help to solve .
1.Tins X,Y,Z each contained some chocolate powder. Mr.John transferred 1/8 of the chocolate powder from tin X to tin Y , then scooped 1/8 of the chocolate powder from tinY into tin Z and finally transferred 1/8 of the chocolate powder from tin Z to tin X. Now there are 49g of chocolate powder in each tin. How much chocolate powder was there in each tin at first ?

Thank you.

After transferred 1/8 of the chocolate powder from tin Z to tin X , tin Z left 7/8 . tin Z --> 7u and tin Z transferred 1u to tin X

In the end
X 7u (49g)
Y 7u (49g)
Z 7u (49g)

Before transferred 1/8 (1u) of the chocolate powder from tin Z to tin X
X 6u
Y 7u
Z 8u

After transferred 1/8 of the chocolate powder from tin Y to tin Z , tin Y left 7/8 . 7/8 --> 7u and tin Y transferred 1u to tin Z

Before transferred 1/8 (1u) of the chocolate powder from tin Y to tin Z
X 6u
Y 8u
Z 7u

After transferred 1/8 of the chocolate powder from tin X to tin Y , tin X left 7/8 . 7/8 --> 6u , as 6u is not divisible by 7 , change tin X 6u --> 6u*7 = 42u , tin Y 8u --> 8u*7 = 56u and tin Z 7u --> 7u*7 = 49u

New ratio
X 42u
Y 56u
Z 49u

7/8 --> 42u ==> 1/8 --> 6u , tin X transferred 6u to tin Y

At first
X 48u
Y 50u
Z 49u

In the end , total powder = X + Y + Z = 3*49 = 147

48u + 50u + 49u --> 147
147u --> 147
1u --> 1

At first
X 48u --> 48g
Y 50u --> 50g
Z 49u --> 49g

[tianzhu]

rrjan:

kindly help me with this qn pls.


Lawrence has some pens. When he packs them into bundles of 5 pens in each bundle, he will have 3 extra pens.
If he packs the into bundles of 9 pens in each bundle, he will need another 8 pens. How many pens are there?

I managed to get the answer 53. But how do I explain the working to my ds?

Many thanks for the kind help rendered:-)

Hi

The answer is 28 pens.

A common method used by students is “Listing”

Find the multiples of 5 + 3.

Find the multiples of 9 – 8.

(25 + 3) and (36 – ------28

Look for a common number, which in this case is 28.

Best wishes

[favianboy]

Need it urgently. Pls help to solve this qns, use assumption and not guess and check. Thanks


A total of 360 teachers and pupils participated in tree planting. Each teacher plated 3 trees and each group of 3 pupils planted 2 trees. If 520 tress were planted, how many pupils are there?

[smartmummy]

favianboy:

Need it urgently. Pls help to solve this qns, use assumption and not guess and check. Thanks


A total of 360 teachers and pupils participated in tree planting. Each teacher plated 3 trees and each group of 3 pupils planted 2 trees. If 520 tress were planted, how many pupils are there?

find the solution here
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&p=951867&hilit=tree+planted#p951867

[smartmummy]

smartmummy:

janicelhl:

A fruitseller had twice as many apples as pears. After he sold 168 apples and 24 pears, he had half as many apples as pear. How many pears did he have left?

After,
A [ ]
P [ ][ ]

Before
A [ u] [ ][24][ ][ ][24]
P [ ][ ] [24]

3u+24*2=168
u=40
Ans=40*2+24=104

Sorry for earlier solution as am learning with my son.

[Atan]

Pls assist to solve the flwg Qn:


Ben has a carton containing some red and green apples. if he adds in 10 red apples, 0.6 number of apples in the carton will be green apples. If he adds in 30 green apples, 3/4 of the number of apples in the carton will be green apples. How many apples are there in the carton?

[speedmaths.012624com]

Atan:

Pls assist to solve the flwg Qn:


Ben has a carton containing some red and green apples. if he adds in 10 red apples, 0.6 number of apples in the carton will be green apples. If he adds in 30 green apples, 3/4 of the number of apples in the carton will be green apples. How many apples are there in the carton?

Hi,

One possible Solution:
Using the Advanced Model Method
(or Bags and Boxes Method)

If he adds in 10 red apples,
0.6 of the apples in the carton will be green apples,
0.4 of the apples in the carton will be red apples

If he adds in 10 red apples, he could then
put all the green apples into 6 Bags, and
put all the red apples into 4 Bags.

Since he did not actually add in the 10 red apples, he actually has
6 Bags of green apples, and (4 Bags – 10) red apples

Green apples → 6 Bags
Red apples → (4 Bags – 10)

If he adds in 30 green apples,
3/4 of the apples will be green apples,
1/4 of the apples will be red apples,

If he adds in 30 green apples, he could then
put all the green apples into 3 Boxes, and
put all the red apples into 1 Box

Since he did not actually add in the 30 green apples, he actually has
(3 Boxes – 30) green apples, and 1 Box of red apples

Green apples → (3 Boxes – 30)
Red apples → 1 Box

From the above:

Green apples → 6 Bags → (3 Boxes – 30)
Red apples → (4 Bags – 10) → 1 Box

Green apples → 6 Bags → (3 Boxes – 30)
Green apples → 6 Bags + 30 → 3 Boxes ......(Row 1)

Red apples → (4 Bags – 10) → 1 Box
(x 3)
Red apples → (12 Bags – 30) → 3 Boxes .....(Row 2)

Row 2 = Row 1
(12 Bags – 30) → 3 Boxes → 6 Bags + 30 → 3 Boxes

12 Bags – 30 → 6 Bags + 30

(Subtract 6 Bags from both the right and left sides of the equation)

6 Bags – 30 → 0 Bag + 30

(Add 30 to both the right and left sides of the equation)

6 Bags – 0 → 0 Bag + 60
6 Bags → 60
1 Bag → 10

Green apples → 6 Bags
Red apples → (4 Bags – 10)

Ben has 10 Bags – 10 apples = (10 x 10) – 10 = 90 apples in the carton.

Hope this helps.

Cheers

speedmaths.com

PS.
Parents who wish to know more can look for the “PSLE Maths - Advanced Model Method” book.

.

[speedmaths.012624com]

smartmummy:

smartmummy:

[quote=\"janicelhl\"]A fruitseller had twice as many apples as pears. After he sold 168 apples and 24 pears, he had half as many apples as pear. How many pears did he have left?

After,
A [ ]
P [ ][ ]

Before
A [ u] [ ][24][ ][ ][24]
P [ ][ ] [24]

3u+24*2=168
u=40
Ans=40*2+24=104

Sorry for earlier solution as am learning with my son.

[/quote]Hi,

One minor point:

He had 104 pears at first.

He had 80 pears left.

Cheers


speedmaths.com


.

[smartmummy]

Thanks speedmaths.com.