Q&A - PSLE Math
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Thanks a million mama_10...
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u r welcome
hope im giving u the right answer. -
mama_10:
Hiquote=\"Mum1113\"]Hi, kindly help this pls, thanks!
Jack,.Meili and Raj shared some 50 cent coins.
They each had an average of 28 coins.
The total amount of money that Jack and Meili had was $7 more than
the total amount of Jack and Raj had.
If Raj's amount was 4 times of Jack's amount, how much more money
did Meili have than Jack?
Where is this question from?
Please help to confirm the numbers from your source.
Best wishes[/quote]
This is Rosyth 2012 ca1 q14. No ans provided.
my attempt
Total money 28 x 3 x $0.50 = $42
J - u
R - u u u u
M - u u u u $7
1u = ($42 - $5)/9 = 35/9
M-J = 3u +$7 = (3 x 35/9) + $7 = $18 2/3[/quote]
As no guided answer was provided, my son got his answer: $17.50 .
what's the correct answer?[/quote]
my kid got the same answer as yr son, $17.50. -
Jolyn:
here's an alternative solution using Table Heuristics. It is an approach using tabulated values.Dear Guru Master
Appreciate if you could help as soon as possible.... Thanks a million
Every time Nora saved 70 cents, her father put another 20 cents into her savings. When Nora had $23.40 in her savings, how much of it had been put in by her father?
In every question, you have to recognize which topic this question falls under. If you see the keyword \"for every....\", that means it is a ratio question. The keyword here is \"Every time ...\" which means the same as \"for every...\". The word \"every\" should ring a bell that it is a ratio question.
Note: Black fonts represent values transferred directly from the problem sum, Red fonts represents derived or calculated values.
![](\"http://i46.tinypic.com/39axg.png\")
http://i46.tinypic.com/39axg.png\">
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1) Desmond is 1/3 as old as his sister. 6 years later, he will be 2/5 as old as his sister. How old is Desmond now?
2)The ratio of the number of marbles John had to the number of marbles Benny had at first was 2:3. After John gave 18 of his marbles to Benny, John had 3/5 the number of marbles Benny had. How many more marbles did Benny have than John at first?
3)Helen had 30 marbles fewer than Sam. After Sam gave Helen 100 marbles , Helen had twice as many marbles as Sam. How many marbles did Sam have at first?
4)Sally’s monthly salary is $500 more than Betty but their monthly expenditure are the same. Over a period of time, Sally has saved $2700 but Betty has only saved $200. If each of them spends $740 a month. What is Sally’s monthly salary?
5)Kenny and Joo Seng are selling durians at a fruit stall. If Kenny sells 60 durians per day and Joo Seng sells 15 durians per day, Kenny will have 24 durians left when Joo Seng has sold all his durians.
if Joo Seng sells 60 durians per day and Kenny sells 15 durians per day, Kenny will have 204 durians left when Joo Seng has sold all his durians.
a)How many durians does Kenny have?
b)If the durians are sold at 4 for $10, how much money will they earn after selling all their durians? -
pls post in PSLE Q&A thread.
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iamproudparents:
1)1) Desmond is 1/3 as old as his sister. 6 years later, he will be 2/5 as old as his sister. How old is Desmond now?
Current age..........6 years later
Desmond 1u ......... Desmond 2u
Sister 3u .............. Sister 5u
Difference 2u ........ Difference 3u
Since the difference in age remains the same , change the difference in age to the common multiple , 6u
Current age...................6 years later
Desmond 1u*3 = 3u ......... Desmond 2u*2 = 4u
Sister 3u*3 = 9u .............. Sister 5u*2 = 10u
Difference 2u*3 = 6u ........ Difference 3u*2 = 6u
4u - 3u --> 6
1u --> 6
3u --> 3*6 = 18
Desmond is 18 years old now -
iamproudparents:
2)
2)The ratio of the number of marbles John had to the number of marbles Benny had at first was 2:3. After John gave 18 of his marbles to Benny, John had 3/5 the number of marbles Benny had. How many more marbles did Benny have than John at first?
At first...............After John gave 18 of his marbles to Benny
John 2u ....................John 3u
Benny 3u ...................Benny 5u
Total 5u ....................Total 8u
As total no of marbles (before and after John gave 18 of his marbles to Benny) remains the same , change the total no to the common multiple , 40u .
At first...............After John gave 18 of his marbles to Benny
John 2u*8 = 16u ....................John 3u*5 = 15u
Benny 3u*8 = 24u ...................Benny 5u*5 = 25u
Total 5u*8 = 40u ....................Total 8u*5 = 40u
16u - 15u --> 18
1u --> 18
24u - 16u = 8u = 8*18 = 144
Benny had 144 more marbles than John at first -
iamproudparents:
S [---------1u------------][30]
3)Helen had 30 marbles fewer than Sam. After Sam gave Helen 100 marbles , Helen had twice as many marbles as Sam. How many marbles did Sam have at first?
H [---------1u------------]
S [-----1p--------][--70--][30]
H [-----1p--------][--70--]
After Sam gave Helen 100 marbles
S [-----1p--------]
H [-----1p--------][--70--][---100---]
Helen had twice as many marbles as Sam
1p --> 70 + 100 = 170
1p +70 + 30 --> 170 + 70 + 30 = 270
No of marbles that Sam had at first = 270 -
iamproudparents:
Over a period of time ,
4)Sally's monthly salary is $500 more than Betty but their monthly expenditure are the same. Over a period of time, Sally has saved $2700 but Betty has only saved $200. If each of them spends $740 a month. What is Sally's monthly salary?
the difference in savings = 2700 - 200 = 2500
No of months for Sally to save $2700 = 2500/500 = 5
Amount of momey that Sally saved per month = 2700/5 = 540
540 + 740 = 1280
Sally's monthly salary = $1280
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