Tutor MathsGuru: Ask me for your burning Maths questions!

[iFruit]

Daddy:

Hi,


Another ratio problem to solve :? Please help. Thanks

1. 2/5 of P is equal to 3/10 of Q. 1/2 of R is equal to Q. Express P as a simple ratio to R

Thanks

2/5 x P = 3/10 x Q -------------(1)
1/2 x R = Q --------------------(2)

Substituting (2) in (1), we get

2P/5 = 3/10 x (R/2) = 3R/20

after cross multiplying,

P/R = (5x3)/ (2x20) = 3/8

P:R = 3:8


HTH

[Brenda10]

Daddy:

hi Brenda10,


very sorry. I did not understand the working. any other simplest way of explaining. Thanks

O : P
9 : 5 (at First)
-240 -200
12 : 5 (at the end)

O 45u 1200 (9 x 5, 240 x 5)
P 60u 2400 (5 x 12, 200 x 12)
Diff 15u = 1200
1u = 80

Oranges Left 9u - 240
720 - 240 = 480

Oranges and pears at first : 14u
14 * 80 = 1120

Thanks answers are correct.

Hi, this question is so called classifed under \"External Change\" Model.

We have to make the final qty 12 parts and 5 parts equal. As such we have to multiply the entire colum by the same number.

Then we have (9 x 5, 240 x 5) and (5 x 12, 200x 12).

Hopefully you can understand and BTW all these strategies and explanation can be found in some assesssment books.

Happy New Year.

[Dharma]

Daddy:

Hi,


Another ratio problem to solve :? Please help. Thanks

1. 2/5 of P is equal to 3/10 of Q. 1/2 of R is equal to Q. Express P as a simple ratio to R

Thanks

2/5 P = 3/10 Q
P/Q = 3/10 x 5/2 = 3/4
P : Q = 3 : 4

Q = 1/2 R
Q/R = 1/2
Q : R = 1 : 2 = 4 : 8
so, P : R = 3 : 8

[Tang]

Dharma:

Daddy:

Hi,


Another ratio problem to solve :? Please help. Thanks

1. 2/5 of P is equal to 3/10 of Q. 1/2 of R is equal to Q. Express P as a simple ratio to R

Thanks

2/5 P = 3/10 Q
P/Q = 3/10 x 5/2 = 3/4
P : Q = 3 : 4

Q = 1/2 R
Q/R = 1/2
Q : R = 1 : 2 = 4 : 8
so, P : R = 3 : 8

Hi,

2/5 x 3/3 = 6/15

3/10 x 2/2 = 6/20

1/2 x 20/20 = 20/40

15 :40 = 3 :8

[pineapple tarts]

Good day Maths Guru,


I am stucked with this one.

A group of children paid a total of $364 for a trip. Each girl paid $10 and each boy paid a dollar less. If there were 6 girls more than boys, how many boys were there in the group?

Other than using the guessing method (draw the table), is there other solution?

Many thanks

[autolycus]

pineapple tarts:

Good day Maths Guru,


I am stucked with this one.

A group of children paid a total of $364 for a trip. Each girl paid $10 and each boy paid a dollar less. If there were 6 girls more than boys, how many boys were there in the group?

Other than using the guessing method (draw the table), is there other solution?

Many thanks

The price is roughly $10 per person.

So there must be 37 children at least, maybe 38.

Since there are 6 girls more than boys, it must be an even number (boys = girls, plus another 6 girls). Right, so total = 38.

Take out those 6 extra girls, boys + girls (same number of each) = 32.

So there must be 16 boys + 16 girls + 6 extra girls.

Now let's check.

16 x $9 = $144
22 x $10 = $220

Total = $364. Yay!

[pineapple tarts]

autolycus:

The price is roughly $10 per person.

So there must be 37 children at least, maybe 38.

Since there are 6 girls more than boys, it must be an even number (boys = girls, plus another 6 girls). Right, so total = 38.

Take out those 6 extra girls, boys + girls (same number of each) = 32.

So there must be 16 boys + 16 girls + 6 extra girls.

Now let's check.

16 x $9 = $144
22 x $10 = $220

Total = $364. Yay!

Many thanks Autolycus !!

So I have to ask my P4 DD to guess guess with this type of question?

[autolycus]

pineapple tarts:

Many thanks Autolycus !!


So I have to ask my P4 DD to guess guess with this type of question?

Not really...

Think of it this way. If they were all girls at $10, it would be too easy. But let's think about boys as girls with $1 discount ($9 instead of $10).

Then we are trying to find out how many people got a discount.

We know the total number = boys + girls = boys + (boys + 6).

So it is an even total number and it must be more than 36 (paid more than $360, right?). The next highest even number is 38.

If nobody got a discount, that's 38 x $10 = $380.

But the discount is $380-$364 = $16.

So we got total discount of $16, there must be 16 boys (each with $1 discount).

When we check, 16 boys + (16+6) girls, that also gives the same answer!

[autolycus]

I guess the point we can make is that for such problems, we can try many methods. It depends on what your DD’s preferred way of thinking really is.


Hope that helps!

[kancheongmum]

pineapple tarts:

Good day Maths Guru,


I am stucked with this one.

A group of children paid a total of $364 for a trip. Each girl paid $10 and each boy paid a dollar less. If there were 6 girls more than boys, how many boys were there in the group?

Other than using the guessing method (draw the table), is there other solution?

Many thanks

Hi pineapple tarts

I have another method that use reasoning, alternative way of looking at this type of question.

Given that there were 6 more girls, we take away the amount paid by the 6 girls from the total $364

$364 - $60 = $304

So $304 is the amount paid by the equal no. of girls and boys.

1 group --- 1 boy and 1 girl --- $10 + $9 = $19

No. of group ---- $304/$19 ----- 16

So there are 16 boys and 22 girls

Hope this helps