Q&A - PSLE Math

[Musicstar]

How to get 7u each? I do not understand.

jieheng:

Musicstar:

Please help.Thank you

Q17 ) Jane and Iris had 255 sweets altogether. Jane had 15 more sweets than Iris. Jane gave away 25% as many sweets as Iris. She was left with twice as many sweets as Iris.
(a) How many sweets did Iris give away?
(b) How many sweets did Jane have in the end?

J [-----------------][15]
I. [-----------------]

J [][---------------][15]
I. [][][][][---------]

J [][----][15][----][15]
I. [][][][][15][----]

J [][][][][15][][][][15] --> 7u + 30
I. [][][][][15][][][] --> 7u + 15

7u + 30 + 7u + 15 --> 255
14u --> 210
1u --> 15

a)

No of sweets that Iris gave away = 4u = 4*15 = 60

b)

No of sweets that Jane had in the end = 6u + 30 = 6*15 + 30 = 120

[MathIzzzFun]

Musicstar:

Please help.Thank you


Q17 ) Jane and Iris had 255 sweets altogether. Jane had 15 more sweets than Iris. Jane gave away 25% as many sweets as Iris. She was left with twice as many sweets as Iris.
(a) How many sweets did Iris give away?
(b) How many sweets did Jane have in the end?

At first,
Iris's sweets --> (255-15) / 2 = 120
Jane's sweets --> 120 + 15 = 135

In the end,
Number of sweets given away, Jane : Iris --> 1 unit : 4 units
Number of sweets left, Jane : Iris --> 2 parts : 1 part

Jane's sweets --> 1 unit + 2 parts = 135 --- (1)
Iris's sweets --> 4 units + 1 part = 120 ----- (2)

(2) x 2 --> 8 units + 2 parts = 240 ---- (3)
(3) - (1) --> 7 units = 105, 1 unit --> 15

1 part --> 120 - 4 x 15 = 60

Number of sweets given away by Iris --> 4 x 15 = 60

Number of sweets Jane had, in the end --> 2 x 60 = 120

cheers.

[YumYum]

Hi, can someone pls help with this question:


Father has given Claire and Jane each a certain amount of money to spend. If Claire spends $30 each day and Jane spends $20 each day, Claire would have $100 left by the time Jane spends all her money. If Claire spends $20 each day and Jane spends $30 each day, Claire would have $600 left by the time Jane spends all her money. Find the total amount of money given to Claire. thks.

[YumYum]

Hi, can someone pls help with this Qn? thks


http://i34.tinypic.com/14jchs9.jpg\">

[MathIzzzFun]

YumYum:

Hi, can someone pls help with this question:


Father has given Claire and Jane each a certain amount of money to spend. If Claire spends $30 each day and Jane spends $20 each day, Claire would have $100 left by the time Jane spends all her money. If Claire spends $20 each day and Jane spends $30 each day, Claire would have $600 left by the time Jane spends all her money. Find the total amount of money given to Claire. thks.

Similar questions here-


http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8940

cheers.

[ozora]

Need help:

q1) Doreen n Joyce started jogging at 7 am round 400m track. Doreen stopped jogging at 7.20am. By then, Joyce covered 2/3 of the distance completed by Doreen. Doreen ave speed was 30m/min faster than Joyce. How many rounds of track had each of them completed?
2) speed of a car was 60km/h while the speed of van was 45km/h. They started from town P at the same time and travelled along the same route towards town Q. The car reached town Q 1 2/3h earlier than the can. What was the distance travelled by the van when the car reached town Q?

[MathIzzzFun]

YumYum:

Hi, can someone pls help with this Qn? thks


http://i34.tinypic.com/14jchs9.jpg\">

For every length of 350cm(7 x 50cm ropes, 5 x 70 cm rope)

Number of black flags -> 7 x 2= 14
Number of white flags -> 5 x 5 = 25
25-14=. 11 --> 11 more white flags
total --> 39 flags

number of 350cm groups
-> 220 ÷ 11 = 20

total number of black and white flags --> 20 x 39 = 780

cheers.

[tianzhu]

Questions involving “Two ifs” or “Double if ”


Questions on “Two ifs” or “Double if ” are commonly found in past years test papers.

This question posted by Musicstar is certainly an interesting one.

Vicky and her sister have a sum of money . If Vicky gives $120 to her sister, she will have 3 times as much money as her sister. If Vicky gives an additional $40 to her sister, she will have $240 more than her sister. How much money does her sister have?

I’ll use it as an illustration. Please refer to attached slide.

I’ve also spent some time to dig out some questions on “DI” in KSP so that students can have some easy reference.

Hope this helps.

Best wishes

Questions on DI (KSP)

1) Jack and Aqil had some game cards. If Jack gave Aqil 52 cards, he would have the same number of cards as Aqil. If Aqil gave Jack 34 cards, the ratio of the number of cards Aqil had to the number of cards Jack had would be 3:7.How many cards did Jack have at first?(267)

2) If Ahmad gives Pillay 17 marbles, the ratio of his marbles to that of Pillay's will be 4:7. If Ahmad gives Pillay 5 marbles, both will have the same number of marbles. How many marbles does Ahmad have?(49)

3) Ben and Marcus received some money from their mother. Marcus would have $64 more than Ben if Ben gave 2/5 of his share to Marcus. Marcus would have $144 more than Ben if Ben gave 2/3 of his share to Marcus. How much money did Ben receive from his mother?(150)

4) Bottle A and bottle B both contain some juice.
If 1.3 litre of juice was poured into bottle A, the volume of juice in A will be 1.6 times that of the volume of the juice in bottle B.
If 480 ml of juice was poured into bottle B, the volume of juice in bottle B will be 1.8 times that of the volume of the juice in bottle A.
(a) What is the volume of juice in bottle A? (Ans. 1.1 litre)
(b) what is the difference in the volume of juice in both bottles? (Ans: 0.4 litre)

5) Mrs Tan has some pencils. If she packs them into bundles of 5 pencils in each bundle, she will have 4 extra pencils. If she packs them into bundles of 9 pencils in each bundles, she will need 7 more pencils. How many pencils are there? (29)

6) Keith and Shawn each have some money. If Keith spends $38, the ratio of the amount of money Keith has to the amount of money Shawn has will become 2:5. If Shawn spends $38, the ratio will become 8:13. How much money does each boy have? (152,285)

7) 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, there will be 70% of chocolate sweets in the bag. How many vanilla and chocolate sweets does she have?(210)

If Sam gives Terry $350, he will have 4 times as much money as Terry. If Sam gives Terry $550, he will have thrice as much money as Terry. How much money does Sam have ?(3200)

9) Alicia and Bruce are given some money each. If Alicia spends three times as much as Bruce, She will have $1000 more when Bruce has spent all his money. If Alicia spends half of what Bruce spends, she will have $2200 when Bruce has spent all his money. What is the total sum of money given to Alicia and Bruce? (2440 ,480)

10) Jack and Jill owned a chicken farm each. If Jack and Jill sold 60 chickens and 30 chickens respectively in a day, Jack would have 300 chickens left when Jill has sold all her chickens. If Jack sold 30 chickens a day and Jill sold 60 chickens a day, Jack would have 930 chickens left when Jill has sold all her chickens. Find the number of chickens Jack has on his farm. (1140)

11) Tammy and Sharon have some money. If Tammy spent $60 each day and Sharon spent $30 each day, Tammy is left with $400 when Sharon spent all her money. If Sharon spent $60 each day and Tammy spent $30 each day, Tammy is left with $1150 when Sharon spent all her money. How much money do the two girls have? (1900)

12) Sonia has some money to buy some photo albums and photo frames.
If she buys 7 similar photo albums and 3 similar photo frames, she will be short of $27.10.
If she buys 2 similar photo albums and 5 similar photo frames, she will have $19 left.
If a photo frame costs $8.20, how much money does Sonia have?(85)

http://farm9.staticflickr.com/8248/8665075086_b33349a259_z.jpg\">

[YumYum]

MathIzzzFun:

YumYum:

Hi, can someone pls help with this question:


Father has given Claire and Jane each a certain amount of money to spend. If Claire spends $30 each day and Jane spends $20 each day, Claire would have $100 left by the time Jane spends all her money. If Claire spends $20 each day and Jane spends $30 each day, Claire would have $600 left by the time Jane spends all her money. Find the total amount of money given to Claire. thks.

Similar questions here-


http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8940

cheers.

thank you

[YumYum]

MathIzzzFun:

YumYum:

Hi, can someone pls help with this Qn? thks


http://i34.tinypic.com/14jchs9.jpg\">

For every length of 350cm(7 x 50cm ropes, 5 x 70 cm rope)

Number of black flags -> 7 x 2= 14
Number of white flags -> 5 x 5 = 25
25-14=. 11 --> 11 more white flags
total --> 39 flags

number of 350cm groups
-> 220 ÷ 11 = 20

total number of black and white flags --> 20 x 39 = 780

cheers.

Thank you for yr help :xedfingers: