Q&A - P5 Math
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janicelhl:
1.64-0.84=0.8hi please help:
Abdul bought 4 times as many candy bars as chocolate bars. The total mass of candy bars and chocolate bars was.1.64kg. The mass of chocolate bars was 0.84kg heavier than that of the candy bars. The mass of 1 bar of chocolate bar wad 0.228kg heavier than 1 bar of candy bar. Find the number of chocolate bars that Abdul bought.
0.8/2=0.4(mass of candy bars)
0.4/4=0.1(mass of one candy bar)
0.4+0.84=1.24(mass of chocolate bars)
1.24-0.1=1.14
1.14/0.228=5 -
Some ratio questions… Please help. TIA
Mr Lim gave some money to his two sons, Henry and Gary. If Henry gave $12 to Gary, they would have the same amount of money. If Gary gave $12 to Henry, the ratio of Henry’s amount to Gary’s amount would be 2 : 1. How much money did each boy have?
The ratio of the number of pens to the number of erasers in a shop was 5 : 1. When 10 pens were sold and the shopkeeper bought 10 more erasers, there is twice as many pens as erasers. How many more pens than erasers were there in the shop in the end?
In a ballroom, the ratio of the number of dancers to the number of non-dancers is 7 : 5. The ratio of the number of male dancers to the number of female dancers is 8 : 3. If 4/5 of the non-dancers are women and there are 56 male dancers, how many men and women are there in the ballroom? -
shann2:
Hi shann2,Some ratio questions... Please help. TIA
The ratio of the number of pens to the number of erasers in a shop was 5 : 1. When 10 pens were sold and the shopkeeper bought 10 more erasers, there is twice as many pens as erasers. How many more pens than erasers were there in the shop in the end?
One possible method, copied from the book \"PSLE Maths - Advanced Model Method\" which you can browse through at any Popular Book store.
Let there be 5 Bags of pens at first.
Let there be 1 Bag of erasers at first.
(Each of the 6 Bags contain the same number of items [pens/erasers])
(The ratio of pens to erasers was 5:1)
Changes:
10 pens were sold and the shopkeeper bought 10 more erasers
Let there be 2 Boxes of pens in the end.
Let there be 1 Box of erasers in the end.
(Each of the 3 Boxes contain the same number of items [pens/erasers])
(there is twice as many pens as erasers [in the end])
Pens:
5 Bags - 10 pens = 2 Boxes .......... (Row 1)
Erasers:
1 Bag + 10 erasers = 1 Box
(x 2)
2 Bags + 20 erasers = 2 Boxes ...........(Row 2)
Row 1 = Row 2
2 Boxes = 2 Boxes
5 Bags - 10 = 2 Boxes = 2 Bags + 20 = 2 Boxes
5 Bags - 10 = 2 Bags + 20
5 Bags = 2 Bags + 30
3 Bags = 30 items (pens / erasers)
1 Bag = 10 items (pens / erasers)
1 Bag = 10 erasers (at first)
5 Bags = 50 pens (at first)
Can you continue from here?
Cheers
speedmaths.com
. -
shann2:
Some ratio questions... Please help. TIA
Mr Lim gave some money to his two sons, Henry and Gary. If Henry gave $12 to Gary, they would have the same amount of money. If Gary gave $12 to Henry, the ratio of Henry’s amount to Gary’s amount would be 2 : 1. How much money did each boy have?![](\"http://i41.tinypic.com/2vm7kg9.png\")
http://i41.tinypic.com/2vm7kg9.png\">
1u=4*12=48
Henry=1u+3*12=48+36=84
Gary=1u+12=48+12=60 -
shann2:
D:NDSome ratio questions... Please help. TIA
In a ballroom, the ratio of the number of dancers to the number of non-dancers is 7 : 5. The ratio of the number of male dancers to the number of female dancers is 8 : 3. If 4/5 of the non-dancers are women and there are 56 male dancers, how many men and women are there in the ballroom?
7:5
MD:FD
8:3
MD=56
8u=56
1u=7
3u=21
D=MD+FD=56+21=77
7P=77 [I use P as the 1P is different from 1U]
P=11
5P=55
D+ND=77+55=132
There are 132 men and women in the Ballroom -
shann2:
At firstSome ratio questions... Please help. TIA
The ratio of the number of pens to the number of erasers in a shop was 5 : 1. When 10 pens were sold and the shopkeeper bought 10 more erasers, there is twice as many pens as erasers. How many more pens than erasers were there in the shop in the end?
Pens 5u
Erasers 1u
Total 6u
After 10 pens were sold and the shopkeeper bought 10 more erasers , total no of pens and erasers remained the same .
In the end
Pens 2u ------------>Pens 4u
Erasers 1u --------->Erasers 2u
Total 3u ------------>Total 6u
5u - 4u = 1u
1u --> 10
Pens 4u , Erasers 2u
Different = 4u - 2u = 2u = 2*10 = 20 -
shann2:
Concept: External changed quantitySome ratio questions... Please help. TIA
The ratio of the number of pens to the number of erasers in a shop was 5 : 1. When 10 pens were sold and the shopkeeper bought 10 more erasers, there is twice as many pens as erasers. How many more pens than erasers were there in the shop in the end?
P:E
5:1 [5U:1U]
-10 +10
2:1 [2P:1P]
Make the parts equal
5U-10=2U+20
3U=30
1U=10
1P=1U+10=20
There were 20 more pens than erasers in the end -
smartmummy:
D:NDshann2:
Some ratio questions... Please help. TIA
In a ballroom, the ratio of the number of dancers to the number of non-dancers is 7 : 5. The ratio of the number of male dancers to the number of female dancers is 8 : 3. If 4/5 of the non-dancers are women and there are 56 male dancers, how many men and women are there in the ballroom?
7:5
MD:FD
8:3
MD=56
8u=56
1u=7
3u=21
D=MD+FD=56+21=77
7P=77 [I use P as the 1P is different from 1U]
P=11
5P=55
D+ND=77+55=132
There are 132 men and women in the Ballroom
Hi smartmummy, can u pl let me know why is 7P=77... -
Jamesbond:
D:NDsmartmummy:
[quote=\"shann2\"]Some ratio questions... Please help. TIA
In a ballroom, the ratio of the number of dancers to the number of non-dancers is 7 : 5. The ratio of the number of male dancers to the number of female dancers is 8 : 3. If 4/5 of the non-dancers are women and there are 56 male dancers, how many men and women are there in the ballroom?
7:5
MD:FD
8:3
MD=56
8u=56
1u=7
3u=21
D=MD+FD=56+21=77
7P=77 [I use P as the 1P is different from 1U]
P=11
5P=55
D+ND=77+55=132
There are 132 men and women in the Ballroom
Hi smartmummy, can u pl let me know why is 7P=77...[/quote]
cos D:ND-----7:5
number of dancers is 77 that is equal to 7 units -
shann2:
Hi Shann2, one more method for your child to consider ....Some ratio questions... Please help. TIA
The ratio of the number of pens to the number of erasers in a shop was 5 : 1. When 10 pens were sold and the shopkeeper bought 10 more erasers, there is twice as many pens as erasers. How many more pens than erasers were there in the shop in the end?
The question tells us that the shopkeeper now has twice as many pens as erasers. We further know that this is after the shopkeeper has bought 10 more erasers. We therefore start off the problem-solving as follows:-
\"NOW\" Position: (i.e. after selling 10 pens and buying 10 erasers)
Pens: ( 2 units + 20 )
Erasers: ( 1 unit + 10 )
\"AT FIRST\" Position: (i.e. before selling 10 pens and buying 10 erasers),
Pens: ( 2 units + 20 + 10 )
Erasers: ( 1 unit )
The question further tells us that the ratio of pens to erasers was 5 : 1 AT FIRST.
hence, we can deduce that:-
5 units = 2 units + 30
3 units = 30
1 unit = 10
Hence, the shopkeeper NOW has
(2 units + 20) or 40 pens; and (1 unit + 10) or 20 erasers.
The shoppers has 20 more pens than erasers in the end.
I hope your child will find this method simpler.
Best Regards,
iCreative Math
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