Q&A - P5 Math

[YumYum]

MathIzzzfun> thanks for highlighting…I’m so muddle-headed.


It’s OK, DD just managed to figure out how to do it. thanks and apologies.

[Udon]

MathIzzzFun:

Udon:

pls help...Thanks in advance.


Q1. In a Maths Olympiad, Team A and Team B each has an equal number of pupils. The total number of pupils in each team is less than 10. The average score of the pupils in Team A is 48 marks. The average score of the pupils in Team B is 62 marks. The total score of Team B is 42 marks more than that of Team A.

Find the number of pupils in each team.

number of pupils in each team = 42/(62-48) = 3

cheers.

MathIzzzFun,
Thanks for your help,
Is it the standard formula for this type of question?
Can I use guess & check method?

[MathIzzzFun]

Udon:

MathIzzzFun:

Q1. In a Maths Olympiad, Team A and Team B each has an equal number of pupils. The total number of pupils in each team is less than 10. The average score of the pupils in Team A is 48 marks. The average score of the pupils in Team B is 62 marks. The total score of Team B is 42 marks more than that of Team A.

Find the number of pupils in each team.

number of pupils in each team = 42/(62-48) = 3

cheers.

MathIzzzFun,
Thanks for your help,
Is it the standard formula for this type of question?
Can I use guess & check method?

not really a standard formula..
since there are equal number of pupils in each team, the difference in the average in the two teams is equal to the difference in individual score (62-48). So, dividing the total difference in score (42) will thus give the number of pupils in each group.. concept is similar to \"there are equal number of pens and pencils. If each pen cost $0.30 more than a pencil, how many pens if the total cost of pens is $3.00 more than that of the pencils.\"

cheers.

[aps]

Dear all

Please help me with these two qns.
1)The head of a crocodile is 29cm long. Its tail is as long as its head plus one-half of the length of its body together. The body is as long as the head and its tail together. What is the length of the crocodile?


2)Richard, Dan and Tom shared a bag of marbles. Richard received 60 marbles and Tom received 25% less marbles than Dan. Later, Richard gave 28 marbles to be shared by Dan and Tom. As a result, Tom still has 25% fewer marbles than Dan and the number of marbles Dan receives increases by 40%. How many marbles were there in the bag?

Thanks!

[cimman]

ozora:

Can anyone help to verify my answer of these following questions:

1.I bakes 18 more fruit cakes than choco cakes. After giving away 35 cakes of each type, the number of choco cakes became 75% of the number of fruit cakes. How many choco cakes is left?
Answer 81.

if you don't mind doing a little bit of algebra, here's one way of looking at things.
First step is to fill in the table based on information from the problem sum:
http://i48.tinypic.com/2n0puu1.png\">

next, circle the Difference Statement, that's the part where they say somebody has xx more than somebody else, in this case, fruit cake more than choco cake. The Difference Statement always gives you an equation.
Then fill in the relevant blank boxes that was circled, using the following equation:
Before + Transfer = After
or
Before = After - Transfer (as in this case)

... 18 more fruit cakes than choco cakes translates to:
Fruit cake - Choco cake = 18
http://i48.tinypic.com/2v92irp.png\">

point to note: in problems with percentages, always find a box to store the 100% value. The 100% is the reference point, so it must be represented in the table. For every percentage value, there is always a corresponding 100% value.

you can use this method for similar problem types. The method is independent of the Transfer values or the After values, the derivation of the logic/equation remains the same.

[cimman]

alternatively, you can also simplify the 75% value to 3/4. This is how the table will look like with the 3/4 value. I put in the 75% value so that it is easier to see the direct correlation of the solution to the problem sum. Either way is fine, though the percentage expressed as a simplified fraction is slightly easier to calculate.


http://i46.tinypic.com/2l89flj.png\">

[Udon]

MathIzzzFun:

Udon:

[quote=\"MathIzzzFun\"]

Q1. In a Maths Olympiad, Team A and Team B each has an equal number of pupils. The total number of pupils in each team is less than 10. The average score of the pupils in Team A is 48 marks. The average score of the pupils in Team B is 62 marks. The total score of Team B is 42 marks more than that of Team A.

Find the number of pupils in each team.

number of pupils in each team = 42/(62-48) = 3

cheers.

MathIzzzFun,
Thanks for your help,
Is it the standard formula for this type of question?
Can I use guess & check method?

not really a standard formula..
since there are equal number of pupils in each team, the difference in the average in the two teams is equal to the difference in individual score (62-48). So, dividing the total difference in score (42) will thus give the number of pupils in each group.. concept is similar to \"there are equal number of pens and pencils. If each pen cost $0.30 more than a pencil, how many pens if the total cost of pens is $3.00 more than that of the pencils.\"

cheers.[/quote]
MathIzzzFun,

Thanks for the explanation.....

[cimman]

Udon:

pls help...Thanks in advance.


Q1. In a Maths Olympiad, Team A and Team B each has an equal number of pupils. The total number of pupils in each team is less than 10. The average score of the pupils in Team A is 48 marks. The average score of the pupils in Team B is 62 marks. The total score of Team B is 42 marks more than that of Team A.

Find the number of pupils in each team.

here's another way of looking at the problem. I always start off with a table, it helps to organize the information in a useful way.
First you need to translate this sentence to an equation:
http://i47.tinypic.com/1dpmr.png\">
I call this the Difference Statement simply because it states the difference between 2 parameters. It is very common in problem sums.

Then fill up the table with information from the problem sum:

http://i45.tinypic.com/xkqedc.png\">

Next, circle the Difference Statement and fill in the blank boxes that was circled by using this Average formula:
Total/Quantity = Average
or
Total = Average x Quantity
http://i46.tinypic.com/iemu8l.png\">

You'll find that information in most Average problems will fit into this table nicely. Fill in the table, circle the equation, then solve the equation.

[MathIzzzFun]

aps:

Dear all

Please help me with these two qns.
1)The head of a crocodile is 29cm long. Its tail is as long as its head plus one-half of the length of its body together. The body is as long as the head and its tail together. What is the length of the crocodile?


Thanks!

Head --> 29cm
Body --> 2 units
Tail --> 29 cm + 1 unit
Total length --> 3 units + 58cm

Body is as long as head and its tail :
2 units = 29 + 29 + 1 unit
1 unit --> 58

Total length --> 232 cm

cheers.

[MathIzzzFun]

aps:

Dear all

Please help me with these two qns.

2)Richard, Dan and Tom shared a bag of marbles. Richard received 60 marbles and Tom received 25% less marbles than Dan. Later, Richard gave 28 marbles to be shared by Dan and Tom. As a result, Tom still has 25% fewer marbles than Dan and the number of marbles Dan receives increases by 40%. How many marbles were there in the bag?

Thanks!

At first,
Tom : Dan = 75:100 = 3:4 --> 15u : 20u -- total 35u

In the end,
Dan --> 20u x 7/5 = 28u
Tom --> 3/4 x 28u = 21u
Total 49u

49u-35u = 14u --> 28 , 1u --> 2

Total number of marbles --> 60 + 35 x 2 = 130

cheers.