Q&A - PSLE Math

[tianzhu]

stary:

20% of John's savings is $120 more than 30% of Brian's savings. After John spent 5/6 of his savings and Brian spent 1/2 of his savings. John has $20 more than Brian. Find John's savings at first.

Hi stary

Again, due to time constraints, I’ll not draw the MD but will provide you with some pointers to draw the MD yourself.

To avoid working with decimals, I will use equivalent ratios to change 3/10 to 6/20 .
Therefore, for Brian , 30% of 20 units --------- 6 units

20% or 1 part of John’s savings --------- 6 units + 120
Hence, John’s savings --------- 30 units + 600

After John spent 5/6 of his savings
Savings left ------- 5 units + 100

After Brian spent 1/2 of his savings.
Savings left ------- 10 units

John has $20 more than Brian.
5 units + 100 -------- 10 units + 20
5 units --------80
1 unit -------16

John’s savings -------- (30*16) + 600 -------- 1080

If you need more clarification, please let me know.

Best wishes

[tianzhu]

small:

Hi Stary,


You are welcome...Tianzhu is my 'shi fu'..

:celebrate:

Hi small

Alamak, pai seh, how can I be your 'shi fu'?

My solutions all agak agak types, learned out of necessity because my money not enough to send my kid for tuition.

You have a boy in P5 this year, so you have about two years to actively read on primary maths, you can only get better.

For me, I’ve stopped reading primary maths since October 2009, what’s being left in my old memory is residues from my previous readings, very soon will leak out from my rusty memory.

I am sure members look forward to see more solutions from you.

Best wishes

[stary]

tianzhu:

stary:

20% of John's savings is $120 more than 30% of Brian's savings. After John spent 5/6 of his savings and Brian spent 1/2 of his savings. John has $20 more than Brian. Find John's savings at first.

Hi stary

Again, due to time constraints, I’ll not draw the MD but will provide you with some pointers to draw the MD yourself.

To avoid working with decimals, I will use equivalent ratios to change 3/10 to 6/20 .
Therefore, for Brian , 30% of 20 units --------- 6 units

20% or 1 part of John’s savings --------- 6 units + 120
Hence, John’s savings --------- 30 units + 600

After John spent 5/6 of his savings
Savings left ------- 5 units + 100

After Brian spent 1/2 of his savings.
Savings left ------- 10 units

John has $20 more than Brian.
5 units + 100 -------- 10 units + 20
5 units --------80
1 unit -------16

John’s savings -------- (30*16) + 600 -------- 1080

If you need more clarification, please let me know.

Best wishes

Hi Tianzhu,

Thank u so much for yr solutions. Had learnt a great deal fm yr methods, and applied to the rest of my pending questions similar to that. So much to learn fm you n Small.

Regards,
Stary

[tianzhu]

stary:

Hi Tianzhu,

Thank u so much for yr solutions. Had learnt a great deal fm yr methods, and applied to the rest of my pending questions similar to that. So much to learn fm you n Small.

Regards,
Stary

Hi

You're welcome.

Best wishes

[small]

tianzhu:

small:

Hi Stary,


You are welcome...Tianzhu is my 'shi fu'..

:celebrate:

Hi small

Alamak, pai seh, how can I be your 'shi fu'?

My solutions all agak agak types, learned out of necessity because my money not enough to send my kid for tuition.

You have a boy in P5 this year, so you have about two years to actively read on primary maths, you can only get better.

For me, I’ve stopped reading primary maths since October 2009, what’s being left in my old memory is residues from my previous readings, very soon will leak out from my rusty memory.

I am sure members look forward to see more solutions from you.

Best wishes

Tianzhu,

You are too humble...:celebrate:

In fact, my feeling is your rusty memory far better than mine.

[Dharma]

stary:

Hi all,

I have a question in doubts, need some assistance. Tks u:)

20% of John's savings is $120 more than 30% of Brian's savings. After John spent 5/6 of his savings and Brian spent 1/2 of his savings. John has $20 more than Brian. Find John's savings at first.

If 20% of John’s savings is $120 more than 30% of Brian’s savings
100% of John’s savings is $600 more than 150% of Brian’s savings

After John spent 5/6 of his savings and Brian spent ½ of his savings;
1/6 of John’s savings is $20 more than ½ of Brian’s savings
6/6(100%) of John’s savings is $120 more than 300% of Brian’s savings.

300% of Brian’s savings + $120 = 150% of Brian’s savings + $600
150% of Brian’s savings = $480

John’s savings at first = $480 + $600 = $1080

[JSSK]

Dear bro/ sis,


Can anyone help me with following maths problems? Thanks a million.

Mt. Tan puts up poles from one end of a road to the other at equal distances apart.There are 27 wooden poles. The width of each pole is 10 cm. The distance between 2 poles is 30m. Find the length of the road.

9) Krishnan had 64 coins in his coin box.There were 20-cent coins and 50-cent coins. The total value of all coins was $18.50. How many 20-cent coins and how many 50 cent coins were there?

10) Daisy, Lily & Florence share $268. Lily has $20 more than Daisy and Florence has twice as much as Lily. How much money do Daisy & lily have altogether?

11) Xuxian and Rachel had the same number of marbles. After Rachel gave away 10 marbles and Xuxian gave away 22 marbles, Rachel had 3 times as many marbles as Xuxian. How many marbles did each of them have at first?

12) Gerry had a total of 30 pens and pencils at first. He then decided to exchange all his pens for pencils. If he exchanged every pen for 2 pencils, he would have 48 pencils. How many pens & pencils did he have at first?

5) A carton can hold 850cm3 of grape juice. Grace wants to buy 15 such cartons of grape juice. Every 250cm3 of grape juice costs $1. How much does she have to pay altogether?

6) A sweet cost 15 cents and a packet of 8 similar sweets cost 1. Clement bought exactly 37 sweets. What was the least amount of money that Clement spent on sweets?

[Belle2011]

Dear \"si-fus\",

http://www.orlesson.org/orp/10Ma/2010-P6-Math-SA1-AiTong.pdf

The number of the $100 notes to $5 notes Angel had was 7:4. She exchanged 12 pieces of $100 into some $5 notes. After which, the ratio of the number of $100 notes to $5 notes became 1:16. What was the amount of money Angel had at first?

Thank-you.

Cheers,
Belle.

[Brenda10]

Belle2011:

Dear \"si-fus\",

http://www.orlesson.org/orp/10Ma/2010-P6-Math-SA1-AiTong.pdf

The number of the $100 notes to $5 notes Angel had was 7:4. She exchanged 12 pieces of $100 into some $5 notes. After which, the ratio of the number of $100 notes to $5 notes became 1:16. What was the amount of money Angel had at first?

Thank-you.

Cheers,
Belle.

Hi, we are not 'si-fus' lah and are also in learning process. The following is extracted from DD's working:

$100 : $5
7 : 4
-12 +240
1 : 16

$100} 112U
$5 } 4U 240 + 192

108U = 432
1U = 4
7U = 28
4U = 16

Therefore, (28 x $100) + (16 x $5) = $2880


Thank you

[Belle2011]

Dear brenda10,

May I know why

$100} 112U
$5 } 4U 240 + 192
108U = 432

Thank-you.
Cheers,
Belle.