Q&A - PSLE Math

[thinkgmama]

Hi,

Kindly help with this qn from my daughter’s worksheet.

1) The number of stamps that Mary and Henry had at first was in the ratio 3:1. After Mary bought 56 stamps and Henry sold 15 stamps, Mary then had 6 times as many stamps as Henry. How many stamps did Henry have at first?

2) Ali and Ben shared a sum of money in the ratio of 1:4. If Ali gives Ben $36, Ben will have 6 times as much money as Ali. How much money does Ben have?

[Bunny27]

thinkgmama:

Hi,

Kindly help with this qn from my daughter's worksheet.

1) The number of stamps that Mary and Henry had at first was in the ratio 3:1. After Mary bought 56 stamps and Henry sold 15 stamps, Mary then had 6 times as many stamps as Henry. How many stamps did Henry have at first?

2) Ali and Ben shared a sum of money in the ratio of 1:4. If Ali gives Ben $36, Ben will have 6 times as much money as Ali. How much money does Ben have?

Hi, pls help on this question :

Janice's monthly income is $300 more than Betty's but their monthly expenditures are the same. Over a period of time, Janice saved $1700 while Betty only saved $500.

a) How long does each of them take to save the given amount of money?

b) Given that each of them $1500 per month, what is Janice's monthly income?

Thanks ...

[tianzhu]

Bunny27:

Hi, pls help on this question :

Janice's monthly income is $300 more than Betty's but their monthly expenditures are the same. Over a period of time, Janice saved $1700 while Betty only saved $500.

a) How long does each of them take to save the given amount of money?

b) Given that each of them $1500 per month, what is Janice's monthly income?

Thanks ...

Hi

Good morning.

Janice saved $1700 while Betty only saved $500.

1700 – 500 ------ 1200

Janice's monthly income is $300 more than Betty's

1200/300 ------- 4

They took 4 months.

b)

I think there is some missing word in the highlighted phrase.

Given that each of them spends $1500 per month.

1700/4 ------ 425

Janice’s monthly salary ------ 1500 + 425 ----- 1925

Best wishes

[tianzhu]

thinkgmama:

Hi,

Kindly help with this qn from my daughter's worksheet.

1) The number of stamps that Mary and Henry had at first was in the ratio 3:1. After Mary bought 56 stamps and Henry sold 15 stamps, Mary then had 6 times as many stamps as Henry. How many stamps did Henry have at first?

2) Ali and Ben shared a sum of money in the ratio of 1:4. If Ali gives Ben $36, Ben will have 6 times as much money as Ali. How much money does Ben have?

Hi

Good Morning.

For Q2, you may use MD or UM.

At first
Ali:Ben - ------ 1:4 (5) ------- 7:28 (35)

Change
Ali:Ben ------- -36:+36

In the end
Ali:Ben - ------ 1 :6 (7) ------- 5:30 (35)

The amount of money remains the same before and after.
Make the total number of units the same.

2 units ------ 36
1 unit ------ 18

Ben ------ 28*18 ------ 504

For Q1, please check your question.

I’ve found a similar question to yours, some numbers are different.

If the question is revised as shown, then you may use “Units and Parts’ to solve it.

The number of stamps that Mary and Henry had at first was in the ratio 3 : 1. After Mary bought 36 stamps and Henry sold 20 stamps, Mary then had 5 times as many stamps as Henry. How many stamps did Henry have at first?

At first
Mary’s stamps : Henry’s stamps ----- 3 units:1 unit

Change
Mary’s stamps : Henry’s stamps ----- +36: -20

In the end
Mary’s stamps : Henry’s stamps ----- 5 parts:1 part

3 units + 36 ------ 5 parts

1 unit – 20 ------ 1 part
(x5)
5 units – 100 ------ 5 parts

Equalise the parts or cross multiply.

3 units + 36 ------ 5 units – 100
2 units ------ 136
1 unit ------ 68

Henry ------ 68 stamps (at first)

Now, try to do your question, change 56 to 66.

Best wishes

[2DMommy]

Please help me with these two questions :


1) Sally has a bottle containing some red and blue beads. If she adds another 10 red beads, 60% of the beads in the bottle are blue. If she adds another 30 blue beads, 75% of the beads in the bottle are blue. How many red beads are in the bottle ?

2)Susan has some vanilla and chocolate sweets in her bag. If she adds 20 vanilla sweets into the bag, the percentage of vanilla sweets in the bag becomes 40%. If she adds 30 chocolate sweets in the bag, there will be 70% of chocolate sweets in the bag. How many vanilla and chocolate sweets does she have ?

Thank you !

[tianzhu]

2DMommy:

2)Susan has some vanilla and chocolate sweets in her bag. If she adds 20 vanilla sweets into the bag, the percentage of vanilla sweets in the bag becomes 40%. If she adds 30 chocolate sweets in the bag, there will be 70% of chocolate sweets in the bag. How many vanilla and chocolate sweets does she have ?

Thank you !

Hi

Q2 has been discussed earlier.

Best wishes

http://farm8.staticflickr.com/7007/6742265061_968d15425b_z.jpg\">

[tianzhu]

2DMommy:

Please help me with these two questions :


1) Sally has a bottle containing some red and blue beads. If she adds another 10 red beads, 60% of the beads in the bottle are blue. If she adds another 30 blue beads, 75% of the beads in the bottle are blue. How many red beads are in the bottle ?
Thank you !

Hi

Where is your Q1 from?

Sometimes, the introduction of the word “another” in the conditions can be opened to interpretation.

This question has been floating around regularly in forums.

I have some red and blue ribbons in a bottle.
If I add 20 red ribbons, 60% of my ribbons are blue.
If I add another 60 blue ribbons, 75% of my ribbons are blue.
How many ribbons do I have in the bottle?

Depending on one’s interpretation of the word another in the second condition, one may end up with 180 or 80.

It’ll be helpful if current PSLE students or their parents help to clarify with their school teachers on this question.

For your Q1, I’m more inclined to go for

First scenario
Red beads ------ 2 units – 10
Blue beads ------ 3 units

Second scenario
Red beads ------ 2 units - 10 -------- 1 part
Blue beads ------ 3 units + 30 ------- 3 parts

6 units – 30 -------- 3 units + 30

3 units ------- 60
1 unit ------ 20

Number of red beads -------- 30

Best wishes

[pixiedust]

tianzhu, thank you very much for the tips regarding speed questions. much appreciated !


Appreciate help with this question :
http://i1197.photobucket.com/albums/aa424/pixie_dust8/circle1.jpg\">

[2DMommy]

tianzhu:

2DMommy:

Please help me with these two questions :


1) Sally has a bottle containing some red and blue beads. If she adds another 10 red beads, 60% of the beads in the bottle are blue. If she adds another 30 blue beads, 75% of the beads in the bottle are blue. How many red beads are in the bottle ?
Thank you !

Hi

Where is your Q1 from?

Sometimes, the introduction of the word “another” in the conditions can be opened to interpretation.

This question has been floating around regularly in forums.

I have some red and blue ribbons in a bottle.
If I add 20 red ribbons, 60% of my ribbons are blue.
If I add another 60 blue ribbons, 75% of my ribbons are blue.
How many ribbons do I have in the bottle?

Depending on one’s interpretation of the word another in the second condition, one may end up with 180 or 80.

It’ll be helpful if current PSLE students or their parents help to clarify with their school teachers on this question.

For your Q1, I’m more inclined to go for

First scenario
Red beads ------ 2 units – 10
Blue beads ------ 3 units

Second scenario
Red beads ------ 2 units - 10 -------- 1 part
Blue beads ------ 3 units + 30 ------- 3 parts

6 units – 30 -------- 3 units + 30

3 units ------- 60
1 unit ------ 20

Number of red beads -------- 30

Best wishes

Hi Tianzhu, this question was actually taken from my ds enrichment's homework. We are actually quite confuse too, I will get him to clarify with this teacher and will try to post the method when his teacher goes through with them next week. Thank you

[Winx5015]

Hi,


Got a question on Average,Rate and Speed.

(1). Town P and Town Q are 770km apart. At 6am, a car left Town P for Town Q at an average speed of 70km/h. 6 hours later, a truck set off from Town Q for Town P at an average speed of 80km/h. At what time would the two vehicles pass each other?

Thanks:)