Q&A - PSLE Math

[ozora]

need help in the following question:

1) Tom’s present age is twice more than Sam’s age years ago. Today, Sam’s age is the same number of years ago. How old is Tom now if the sum of their present age is 30?

[MathIzzzFun]

ozora:

need help in the following question:

1) Tom's present age is twice more than Sam's age years ago. Today, Sam's age is the same number of years ago. How old is Tom now if the sum of their present age is 30?

any missing info ?
If the sentence is \"Today, Sam's age is the same as Tom's age same number of years ago\", then
Now, Sam's age --> 12 years, Tom's age --> 18 years
6 years ago, Sam's age --> 6 years, Tom's age --> 12 years.

cheers.

[david59]

starfish53:

Can anyone help me with the following question?


Q1) 3/5 of Bette's money is $324 more than 3/4 of Tina's money.
Bette has twice as much as Tina.
a) How much does Tina have?
b) How much does Bette have?


Thanks in advance.

For this kind of question, I like to use simultaneous equations because you just need to draw the model according to the logical understanding of the facts. This is useful especially for those who are good in interpreting the facts into models.

http://i42.tinypic.com/3169jeu.jpg\">

[ozora]

MathIzzzFun:

ozora:

need help in the following question:

1) Tom's present age is twice more than Sam's age years ago. Today, Sam's age is the same number of years ago. How old is Tom now if the sum of their present age is 30?

any missing info ?
If the sentence is \"Today, Sam's age is the same as Tom's age same number of years ago\", then
Now, Sam's age --> 12 years, Tom's age --> 18 years
6 years ago, Sam's age --> 6 years, Tom's age --> 12 years.

cheers.

yes there is missing infor.thanks for the highlight. sam's age is tom's age the same number of years ago.

[MathIzzzFun]

ozora:

need help in the following question:

1) Tom's present age is twice more than Sam's age years ago. Today, Sam's age is Tom's age the same number of years ago. How old is Tom now if the sum of their present age is 30?

Using units/parts method:

Number of years ago,
Tom's age --> 1p
Sam's age --> 1u

Now,
Tom's age --> 3u
Sam's age --> 1p

Age difference remains the same, therefore,
1p-1u = 3u-1p
1p --> 2u

Now,
Tom's age --> 3u
Sam's age --> 2u
Total --> 5u --- 30
1u --> 6

Tom's age now --> 18

cheers.

[rzz]

hi. Cld someone help me on this pls?

The ratio of the number of Donovan’s stickers to the number of Hong Yi’s stickers is 10:3. After Donovan gave hong Yi 1/5 of his stickers, hong Yi had 30 stickers less than Donovan. How many stickers did Donovan give to Hong yi?
thanks

[jieheng]

rzz:

hi. Cld someone help me on this pls?

The ratio of the number of Donovan's stickers to the number of Hong Yi's stickers is 10:3. After Donovan gave hong Yi 1/5 of his stickers, hong Yi had 30 stickers less than Donovan. How many stickers did Donovan give to Hong yi?
thanks

At first
Donovan 10u
Hong Yi 3u

1/5 of 10u = 2u

Donovan gave 2u to Hong Yi

In the end
Donovan 10u - 2u = 8u
Hong Yi 3u + 2u = 5u

Hong Yi had 30 stickers less than Donovan

8u - 5 u -> 30
3u -> 30
1u -> 10

No of stickers that Donovan gave to Hong yi was 2u -> 2*10 = 20

[ozora]

MathIzzzFun:

ozora:

need help in the following question:

1) Tom's present age is twice more than Sam's age years ago. Today, Sam's age is Tom's age the same number of years ago. How old is Tom now if the sum of their present age is 30?

Using units/parts method:

Number of years ago,
Tom's age --> 1p
Sam's age --> 1u

Now,
Tom's age --> 3u
Sam's age --> 1p

Age difference remains the same, therefore,
1p-1u = 3u-1p
1p --> 2u

Now,
Tom's age --> 3u
Sam's age --> 2u
Total --> 5u --- 30
1u --> 6

Tom's age now --> 18

cheers.

thanks

[ozora]

Need some help in these 2 questions.

Q1. http://i42.tinypic.com/35lsxsg.jpg\">
Q2. Ali and Dee shared a box of blue and green markers equally.
Ali took 3 times as many blue markers as Dee.
The ratio of the number of green markers Dee took to The ratio of the number of green markers Ali took was 9: 5.
what was the ratio of Ali's blue markers to green markers?
the answer given for this is 6:5 but i got 3:5

[MathIzzzFun]

ozora:

Need some help in these 2 questions.

Q1. http://i42.tinypic.com/35lsxsg.jpg\">
Q2. Ali and Dee shared a box of blue and green markers equally.
Ali took 3 times as many blue markers as Dee.
The ratio of the number of green markers Dee took to The ratio of the number of green markers Ali took was 9: 5.
what was the ratio of Ali's blue markers to green markers?
the answer given for this is 6:5 but i got 3:5

Since the box of markers are shared equally, each has same total number of markers

ratio of Ali's green : Dee's green = 5 : 9 -- difference of 4

ratio of Ali's blue : Dee's green = 3 : 1 = 6 : 2 -- difference of 4
(if Ali has 4 more green than Dee, than Dee must also have 4 more blue than Ali since the total is the same)

ratio of Ali's blue : green = 6 : 5

similar question here -- http://www.flickr.com/photos/mathizzzfun/5703951396/

cheers.