Tutor MathsGuru: Ask me for your burning Maths questions!

[MathIzzzFun]

KoalaMummy:

The ratio of the number of apples to oranges is 3:5. Mr Tham bought another 20 apples and 20 oranges and as a result, the ratio of the number of apples to oranges became 7:10. How many apples did Mr Tham have at first? (same 'gap' as the same number of apples and oranges were bought)

Hi KoalaMummy,

hope this helps

http://i55.tinypic.com/o0caih.jpg\">

cheers.

[PiggyLalala]

MathIzzzFun:

KoalaMummy:

The ratio of the number of apples to oranges is 3:5. Mr Tham bought another 20 apples and 20 oranges and as a result, the ratio of the number of apples to oranges became 7:10. How many apples did Mr Tham have at first? (same 'gap' as the same number of apples and oranges were bought)

Hi KoalaMummy,

hope this helps

http://i55.tinypic.com/o0caih.jpg\">

cheers.

Hi MathIzzzFun,
for the question on apple and orange, can i say that the child has to rewrite the before and after ratio a few times as in
Before: Apple: oranges = 3: 5 = 6:10 = 9:15
After: Apple: oranges = 7:10 = 14:20 = 21:30
And see for himself that if the ratio 9:15 and 14:20 are chosen the common difference will then be the same.

Is there any way whereby the child can see immediately that the before ratio has to change to 9:15 and the after ratio has to change to 14:20 so that the common difference is the same?

thank you so much for your time and effort.

[MathIzzzFun]

PiggyLalala:

MathIzzzFun:

[quote=\"KoalaMummy\"]The ratio of the number of apples to oranges is 3:5. Mr Tham bought another 20 apples and 20 oranges and as a result, the ratio of the number of apples to oranges became 7:10. How many apples did Mr Tham have at first? (same 'gap' as the same number of apples and oranges were bought)

Hi KoalaMummy,

hope this helps

http://i55.tinypic.com/o0caih.jpg\">

cheers.

Hi MathIzzzFun,
for the question on apple and orange, can i say that the child has to rewrite the before and after ratio a few times as in
Before: Apple: oranges = 3: 5 = 6:10 = 9:15
After: Apple: oranges = 7:10 = 14:20 = 21:30
And see for himself that if the ratio 9:15 and 14:20 are chosen the common difference will then be the same.

Is there any way whereby the child can see immediately that the before ratio has to change to 9:15 and the after ratio has to change to 14:20 so that the common difference is the same?

thank you so much for your time and effort.[/quote]Hi

For both questions, the difference (in amount of money, and in number of fruits) remain the same. So, we need to look at the difference and equalize them.

For question 1, the \"before\" difference is 2, and \"after\" difference is 3, to equalize multiply the \"before\" ratio by 3, and \"after\" ratio by 2 so that we arrive at the difference of 6 (which is the LCM for 2 & 3) for \"before\" and \"after\".

Similarly, for the 2nd question, the \"before\" difference is 3 and the \"after\" difference is 3 so there is no need to \"equalize\" as it is already the same.

cheers.

[PiggyLalala]

MathIzzzFun:

PiggyLalala:

[quote=\"MathIzzzFun\"][

http://i55.tinypic.com/o0caih.jpg\">

cheers.

Hi MathIzzzFun,
for the question on apple and orange, can i say that the child has to rewrite the before and after ratio a few times as in
Before: Apple: oranges = 3: 5 = 6:10 = 9:15
After: Apple: oranges = 7:10 = 14:20 = 21:30
And see for himself that if the ratio 9:15 and 14:20 are chosen the common difference will then be the same.

Is there any way whereby the child can see immediately that the before ratio has to change to 9:15 and the after ratio has to change to 14:20 so that the common difference is the same?

thank you so much for your time and effort.

Hi

For both questions, the difference (in amount of money, and in number of fruits) remain the same. So, we need to look at the difference and equalize them.

For question 1, the \"before\" difference is 2, and \"after\" difference is 3, to equalize multiply the \"before\" ratio by 3, and \"after\" ratio by 2 so that we arrive at the difference of 6 (which is the LCM for 2 & 3) for \"before\" and \"after\".

Similarly, for the 2nd question, the \"before\" difference is 1 and the \"after\" difference is 1 so there is no need to \"equalize\" as it is already the same.

cheers.[/quote] :thankyou: so much. I have learnt something new again.
:thankyou:

[MathIzzzFun]

PiggyLalala:

MathIzzzFun:

[quote=\"PiggyLalala\"]
Hi MathIzzzFun,
for the question on apple and orange, can i say that the child has to rewrite the before and after ratio a few times as in
Before: Apple: oranges = 3: 5 = 6:10 = 9:15
After: Apple: oranges = 7:10 = 14:20 = 21:30
And see for himself that if the ratio 9:15 and 14:20 are chosen the common difference will then be the same.

Is there any way whereby the child can see immediately that the before ratio has to change to 9:15 and the after ratio has to change to 14:20 so that the common difference is the same?

thank you so much for your time and effort.

Hi

For both questions, the difference (in amount of money, and in number of fruits) remain the same. So, we need to look at the difference and equalize them.

For question 1, the \"before\" difference is 2, and \"after\" difference is 3, to equalize multiply the \"before\" ratio by 3, and \"after\" ratio by 2 so that we arrive at the difference of 6 (which is the LCM for 2 & 3) for \"before\" and \"after\".

Similarly, for the 2nd question, the \"before\" difference is 1 and the \"after\" difference is 1 so there is no need to \"equalize\" as it is already the same.

cheers.

:thankyou: so much. I have learnt something new again.
:thankyou:[/quote]u r welcome :lol:

cheers.

[Chan09]

Need some help on these-

1) A, B and C shared $135. During a trip, A spent 3/5 of her money, B spent 3/4 of his and C spent 2/3 of hers. Given all 3 of them spent the same amt, find the total amt they had left?
Ans: $45

2) in a city, every householdnhas either one or two computers. The ratio of the number of households to the number of computers is 3:5. What fraction of the households has only one computer?
Ans: 1/3

[lizawa]

Chan09:

Need some help on these-

1) A, B and C shared $135. During a trip, A spent 3/5 of her money, B spent 3/4 of his and C spent 2/3 of hers. Given all 3 of them spent the same amt, find the total amt they had left?
Ans: $45

Convert all 3 fractions to same numerator, since all spent the same amount.
3/5 = 6/10
3/4 = 6/8
2/3 = 6/9

total units = 10+8+9 = 27
27 units = 135
1 unit = 135 / 27 = 5
Amount left = (4u + 2u + 3u) = 9u = $45

[Dharma]

Q2)


Number of households : number of computers = 3:5
5 = 2 + 2 + 1 = ( 1 x 2) + ( 1 x 2) + ( 1 x 1)
For every 3 households, 2 households have 2 computers each and the remaining household has 1 computer.

Fraction of household that have 1 computer
= 1/3

[Chan09]

Some help plse:

1) A, B and C have 960 sweets altogether. A gave some of her sweets to B and the number of B sweets doubled. Then B gave some to C and the number of C sweets doubled. If the 3 boys had the same number of sweets in the end, how many sweets did A have at first?
Ans: 560

2) After spending 1/4 of his money on a cake and $120 on decorations, Mr Tan had 1/3 of his money left. How much did he have at first?
Ans: $288

[MathIzzzFun]

Chan09:

Some help plse:

1) A, B and C have 960 sweets altogether. A gave some of her sweets to B and the number of B sweets doubled. Then B gave some to C and the number of C sweets doubled. If the 3 boys had the same number of sweets in the end, how many sweets did A have at first?
Ans: 560

2) After spending 1/4 of his money on a cake and $120 on decorations, Mr Tan had 1/3 of his money left. How much did he have at first?
Ans: $288

Hi

hope this helps

http://i52.tinypic.com/2zfopqd.jpg\">

cheers.