Ratio Question
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pai seh. i toopid.
this is P6 question.
The ratio of the number of adults to the number of children in a bus is 5:3. If 11 more children board the bus and 7 adults alight, there will be an equal number of adults and children in the bus.
How many children are there in the bus to start with?
can anyone think of solution with working?
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5A - 7 = 3C + 11Originally posted by Ito_^:pai seh. i toopid.
this is P6 question.
The ratio of the number of adults to the number of children in a bus is 5:3. If 11 more children board the bus and 7 adults alight, there will be an equal number of adults and children in the bus.
How many children are there in the bus to start with?
can anyone think of solution with working?
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What is 3C ?
Right ?!
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ya..Originally posted by NotFromVenus:5A - 7 = 3C + 11
Right ?!
but not the answer.
i wan find 3C. -
If i not wrong ... the answer is 27....??Originally posted by Ito_^:pai seh. i toopid.
this is P6 question.
The ratio of the number of adults to the number of children in a bus is 5:3. If 11 more children board the bus and 7 adults alight, there will be an equal number of adults and children in the bus.
How many children are there in the bus to start with?
can anyone think of solution with working?
11 + 7 = 18
18 = 2 units
1 unit = 9
for for children at start 3 units = 27
Dun know correct anot ... seems weird tho ... -
3C = 5A -18
Meaning original number of adults - 18 -
Let no. of adults = X
Let no. of children = Y
X/Y = 5/3
X-7 = Y + 11
(5/3)Y - 7 = Y + 11
(5/3)Y - Y = 18
(2/3)Y = 18
Y = 18(3/2) = 27
X = (27)(5/3) = 45 -
if 2C = +18Originally posted by NotFromVenus:3C = 5A -18
Meaning original number of adults - 18
then 3C = +27
5C = 45
Is there such a bus In Singapore ???! 45 adults and 27 kids ???
Double Decker izzit ? -
P6 so complex le ar??
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and i gt phobia of math lor!Originally posted by Rustyhong:P6 so complex le ar??
confirm kill me one.
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This is really the answer ar? I guess my math level is at P3 then ...Originally posted by ^spidee^:Let no. of adults = X
Let no. of children = Y
X/Y = 5/3
X-7 = Y + 11
(5/3)Y - 7 = Y + 11
(5/3)Y - Y = 18
(2/3)Y = 18
Y = 18(3/2) = 27
X = (27)(5/3) = 45 -
dun worry.Originally posted by Rustyhong:This is really the answer ar? I guess my math level is at P3 then ...
mine is at P1. -
one more question..
If Mala gives $25 to Lifen, both of them will have an equal amout of money. On the other hand, if Lifen gives $100 to Mala, then the ratio of Mala's money to Lifen's money will be 7:2. How much money does Mala have to start with?
Answer is $250.. I need is understandable working. -
OMG ... my brain is cracking ... if it was a test and i have time, i will try and error ... with the $25 ... means maybe $125 and $75 ... or $150 and $100 ... slowly i will reach the answer which is $250 ... But it will take some time off the other questions ...
Haiz .... sigh ... Anyway in working life ... ur boss wont ask u this type of questions ba? -
no.Originally posted by Rustyhong:OMG ... my brain is cracking ... if it was a test and i have time, i will try and error ... with the $25 ... means maybe $125 and $75 ... or $150 and $100 ... slowly i will reach the answer which is $250 ... But it will take some time off the other questions ...
Haiz .... sigh ... Anyway in working life ... ur boss wont ask u this type of questions ba?
but i need to teach the kids tmr.
they copy answer sheet one, muz make sure they know.
but i myself oso dunnoe.
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M - 25 = L + 25Originally posted by Ito_^:one more question..
If Mala gives $25 to Lifen, both of them will have an equal amout of money. On the other hand, if Lifen gives $100 to Mala, then the ratio of Mala's money to Lifen's money will be 7:2. How much money does Mala have to start with?
Answer is $250.. I need is understandable working.
(M + 100)/(L - 100) = 7/2
1) M = L + 50
2) 2M + 200 = 7L - 700
2M + 200 = 7(M - 50) - 700
2M = 7M - 350 -700 - 200
2M = 7M - 1250
5M = 1250
M = 250
therefore L = 200 also
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I'll use the infamous bar diagram method:
Q1:
Draw two bars:
Adult: 5 units
Children: 3 units
11 children board the bus. This means the 3 units add 11.
7 adults alight the bus. This means 5 units minus away 7. But note that by "shifting" this 7 adults to the children's side, you can also intepret it as 7 children boarding the bus. So, that obviously you can see something like this:
Adult: 5 units
Children: 3 units + 11 + 7
So, 2 units= 18
1 unit = 9 3 units = 27
There are 27 children initially on the bus.
Q2:
Same logic here. Just draw two bars.
Mala: Longer bar
Lifen: Shorter bar
First sentence: Mala gives Lifen $25 and then both have same money. First draw inside Mala's diagram $25 and "shift" it to Lifen. This means you can again draw another $25 in Mala's diagram. This result = Mala has $50 more than Lifen at the start.
Second sentence: Lifen gives Mala $100, then ratio become 7:2 in favor of Mala. This time, draw $100 in Lifen's diagram and also Mala's diagram. Shift Lifen's $100 to Mala.
Now you shall notice the following:
Mala: 2 units + 100 + 25 + 25 + 100
Lifen: 2 units
This means 100 + 25 + 25 + 100 = 5 units 5 units = $250 1 units = $50
Mala initially has 2 units + 100 + 25 + 25 (Before Lifen gives her $100)
So: 2 units = $100
Mala has initially $100 + $100 + $25 + $25 = $250.