Q&A - PSLE Math

Maths Hub

wahwah:
Hi,

Need help again. Many thanks in advance.

In school A, there were 580 boys and 868 girls. In school B, there were 1420 boys and 382 girls. Some children were transferred from school A to school B. as a result, 40% of the children in school A and 75% of the children in school B were boys. How many children were transferred from school A to school B?

In the end:
School A:
Boys : Girls
2 u : 3 u

School B
Boys : Girls
3 p : 1 p

Total Boys-->580+1420=2000 (2u + 3p)..........(1)
Total Girls-->868+382=1250 (3u + 1p)............(2)

(2)X3: 9 u + 3 p ---> 3750.............................(3)
Comparing (1) and (3)
7 u-->3750-2000=1750
1 u-->1750/7=250
We find 5 units to find the number of students in A in the end.
5 u-->1250

Therefore a total of 580+868-1250=198 was transferred.

Hope that helps.

ftwm

Thanks Maths Hub it was a great help :thankyou:

ftwm

pls help e Q;

The figure is made up of a rectangle and a square. The ratio of the area of the square to the area of the rectangle is 1: 3. A shaded area of 20cm2 is being removed. The ratio of the area of the unshaded square to that of the unshaded rectangle is now 2 : 7. What is the length of the square?

Thank you

ftwm

Q; Tq

Mrs Lee wanted to hang some lanterns. She started by hanging a lantern at each corner of the field as shown in the diagram. The distance between one lantern and another is 190cm along the perimeter of a square field. The perimeter of the field is 380m. She realised that the remaining lanterns are only enough to be hung along 3 sides of the square field. How many lanterns were hung altogether?

tianzhu

Questions involving “Make a Supposition/Assumption”

Hi

I’ve compiled a list of questions on “MS” which members had posted in KSP over the last few years. I’ve shown some possible ways to tackle such questions as shown in attached slides.

Once kids become more familiar with the strategy and and understand the logic, they may do without the tabulated list. Do it the way they are comfortable with.

Hope this helps.

Best wishes

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Questions involving “Make a Supposition/Assumption”
1) There are 85 plates of fried noodles for 80 people. Each adult eats 2 plates of fried noodles and every 3 children share 1 plate of fried noodles. How many adults and how many children are there? (35 adults and 45 children)

2) A total of 360 teachers and pupils participated in tree planting.
Each teacher planted 3 trees and each group of 3 pupils planted 2 trees.
If 520 trees were planted altogether, how many pupils were there? (240)

3) There were 54 cars and bicycles in a car park. Someone removed 1 wheel each from 4 bicycles. As a result, there were 180 wheels left. How many cars were there?(38)

4) A courier company charged $25 for every large parcel and $15 for every
small parcel delivered safely. However, a penalty of $50 was charged for
every damaged parcel regardless of size. This month, the company delivered 120 parcels of which 1/4 of them were small parcels. It collected a total of $2000 after paying a penalty for an equal numbers of large and small parcels.How many large parcels were delivered safely?

5) 20 boys and girls sold tickets for a funfair. Each ticket was sold at $5.Each boy sold 5 tickets and each girl sold 3 tickets. The amount collected by the boys was $20 more than the amount collected by the girls. Find a) how many girls were there in the group b) how many tickets were sold altogether? (8 boys, 12 girls, 76 tickets)

6) A class of 40 pupils helped to carry bundles of old newspapers in an event organised to collect funds for the old folks. Each boy carried 3 stacks of newspapers and each girl carried 2 stacks. Altogether, the boys carried 30 more stacks than the girls. What is the ratio of the number of boys to the number of girls in the class?(11:9)

7) In a Maths quiz, each pupil had to answer 20 questions. 5 points were given for each correct answer and 2 points were taken away from each wrong answer. Mirabel answered all questions and scored 79 points. How many questions did she answer correctly? (17)

There are some goats, chickens and cows in a farm. There are 3 times many chickens as cows. John finds out that among the animals, there are a total of 32 heads and 92 legs. How many goats are there? (18,6 ,8 )

9) I have 38 coins and they are made up of 50-cent and 20-cent coins. Their total value is $13.60. What is the ratio of the number of 20-cent coins to the number of 50-cent coins? (9:10)

10) A group of 24 children sold some tickets for a charity show. Each ticket was sold at $5. Each boy sold 5 tickets and each girl sold 3 tickets. The boys collected $40 more than the girls.
(a) How many girls were there in the group? (14)
(b) How many tickets were sold altogether? (92)

11) After the tsunami, 250 blankets were given out to the people .Three children shared 1 blanket while 2 adults shared 1 blanket. If there were 650 people, how many of them were adults.(650)

12) Mrs B used either 4 red buttons or 2 blue buttons to make each dress. The total number of dresses she made was 35. The total number of red buttons used was 74 more than the total number of red buttons used.
(a) how many red buttons were used altogether?996)
(b) how many blue buttons were used altogether?(22)

13) Kumaran had 64 coins in his coin box. There were 20-cent coins and 50-cent coins. The total value of all the coins was $18.50. How many 20-cent coins and how many 50-cent coins were there?(45,19)

14) At a Science competition, 25 problems were given. Each correct answer earned 4 points, and 2 points were deducted for each incorrect answer. Liang Hong answered all but one of the problems receiving a score of 66. How many correct answers did she have?(19)

15) Mr Lau sells notebooks at $2 each and files at $3 each. After he sold 100 notebooks and files, the amount he collected from the sale of notebooks was $60 more than than the amount collected from the sale of files. How many notebooks did Mr Lau sell?(72)

16) Brandon had 30 spelling tests and collected 36 games cards. With every full marks he scored for a spelling test, he received 2 games cards from his teacher. When he did not score full marks, he had to return 1 games card.
a) how many spelling tests did brandon score full marks?(22)
b) if Brandon wanted to receive a total of 51 games cards, how many spelling tests could he afford not to score full marks?(3)

wahwah

Hi Maths Hub,

Thanks for the help.

Oldschool

NY1969

Pls help this question:–

A man was walking at the speed of 5 km/hr before going on the escalator which is moving at 10km/hr. the man still continue walking, what is his overall walking speed on the escalator?

MathIzzzFun

NY1969:
Pls help this question:--

A man was walking at the speed of 5 km/hr before going on the escalator which is moving at 10km/hr. the man still continue walking, what is his overall walking speed on the escalator?

speed on escalator --> 5 km/h + 10 km/h = 15 km/h

cheers.

MathIzzzFun

ftwm:
pls help e Q;

The figure is made up of a rectangle and a square. The ratio of the area of the square to the area of the rectangle is 1: 3. A shaded area of 20cm2 is being removed. The ratio of the area of the unshaded square to that of the unshaded rectangle is now 2 : 7. What is the length of the square?

Thank you

I presume the removed shaded area is the overlapped area of the square and the rectangle as shown below.

http://i40.tinypic.com/2ibyj3c.png\">

cheers.

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