Q&A - PSLE Math

[Shimmer]

Shimmer:

Hi Tianzhu


Need your help !

Isaac read a book. 1st day he read 2/5 of it unread. 2nd day he read another 24 page of the book . In the end he read was 5/9the pages did not read. If he finish the rest in 4 days. What was the average number he read for the
Rest of the book?

A rectangle tank was empty at first. Tap A was turned at a rate of 6 litres per min. After 2 min, B drain water at 2liters per min. Both tap turned off after 6 min after Zb was turned on. The tank was 28 cm in height and hold56 litres find the height of water level in tank when both tank turn off.


If a director get two designers work together Work will be completed in 6 days. If A work alone it wil completed in 10 days. He hired A to work on it for a few days and remaining B will do it.How many days A must spend so that it is done in 12 1/2 days?

Can someone help on these 3 questions ?

[ozora]

MathIzzzFun:

whitety:

Hi, need help on 2 qns.


2) Huiling had 160 less marbles than George. George gave 75% of his marbles to Huiling. Huiling then gave 20% of her marbles to George. If Huiling had 192 more marbles than George in the end, how many marbles did Huiling have at first?

Thanks!

At first,
Huiling --> 16u
George --> 16u + 160 --- 75% = 12u + 120

After George gave 75% to Huiling
Huiling --> 28u + 120 -- 20% = 5.6u + 24
George --> 4u + 40

After Huiling gave 20% to George
Huiling --> 22.4u + 96
George --> 9.6u + 64
Huiling had 192 more, so
9.6u + 64 + 192 = 22.4u + 96
4u --> 50

at first, Huiling --> 200

cheers.

Sorry may I know how to get 16units for huiling n 12units +120 for75%?

[balu_priya]

Essential:

Hi need some help.... Q1. Among 20 people who are being interviewed , 12 like basketball and 18 like volleyball . All of them like at least one sport. How many people Like both basket ball and volleyball

12+18=30
30-20=10

[speedmaths.012624com]

Shimmer:

Shimmer:

If a director get two designers work together Work will be completed in 6 days. If A work alone it wil completed in 10 days. He hired A to work on it for a few days and remaining B will do it.How many days A must spend so that it is done in 12 1/2 days?

Can someone help on these 3 questions ?

Hi

Q3

One possible solution/method:

A and B take.... 6 days to do 1 job
A takes............10 days to do 1 job

A and B take.... 60 days to do 10 jobs
A takes.............60 days to do 6 jobs

B takes.............60 days to do 4 jobs
(10 - 6 = 4)

B takes.............60 days to do 4 jobs
B takes.............15 days to do 1 job
A takes.............10 days to do 1 job

B takes.............7.5 days to do 0.5 job
A takes.............5 days to do 0.5 job

In this way, they will take 12.5 days to do 1 job.

Hope this helps.

Cheers


speedmaths.com


PS.
There is actually a PSLE Maths book that has 4 chapters to teach students how to solve such/similar Maths questions.
.

[MathIzzzFun]

ozora:

MathIzzzFun:

[quote=\"whitety\"]Hi, need help on 2 qns.


2) Huiling had 160 less marbles than George. George gave 75% of his marbles to Huiling. Huiling then gave 20% of her marbles to George. If Huiling had 192 more marbles than George in the end, how many marbles did Huiling have at first?

Thanks!

At first,
Huiling --> 16u
George --> 16u + 160 --- 75% = 12u + 120

After George gave 75% to Huiling
Huiling --> 28u + 120 -- 20% = 5.6u + 24
George --> 4u + 40

After Huiling gave 20% to George
Huiling --> 22.4u + 96
George --> 9.6u + 64
Huiling had 192 more, so
9.6u + 64 + 192 = 22.4u + 96
4u --> 50

at first, Huiling --> 200

cheers.

Sorry may I know how to get 16units for huiling n 12units +120 for75%?[/quote]One can start with 1 unit or 10 unit but the working will involve fraction/decimal; 16 units was chosen cos it \"matches\" 160 and is divisible by 4.

75% of (16 units + 160) = 3/4 x (16 unit + 160)= 3/4 x 16 + 3/4 x 160 = 12 + 120

cheers.

[ozora]

[

At first,
Huiling –> 16u
George –> 16u + 160 — 75% = 12u + 120

After George gave 75% to Huiling
Huiling –> 28u + 120 – 20% = 5.6u + 24
George –> 4u + 40

After Huiling gave 20% to George
Huiling –> 22.4u + 96
George –> 9.6u + 64
Huiling had 192 more, so
9.6u + 64 + 192 = 22.4u + 96
4u –> 50

at first, Huiling –> 200

cheers.[/quote]
Sorry may I know how to get 16units for huiling n 12units +120 for75%?[/quote]

One can start with 1 unit or 10 unit but the working will involve fraction/decimal; 16 units was chosen cos it "matches" 160 and is divisible by 4.

75% of (16 units + 160) = 3/4 x (16 unit + 160)= 3/4 x 16 + 3/4 x 160 = 12 + 120

cheers.[/quote]
thanks. I have tried using 1 unit and working really involved alot of fractions. THanks for sharing the method.

[Robertpattinsonidle]

what is the solution for these questions?


A rectangle tank was empty at first. Tap A was turned at a rate of 6 litres per min. After 2 min, B drain water at 2liters per min. Both tap turned off after 6 min after Zb was turned on. The tank was 28 cm in height and hold 56 litres find the height of water level in tank when both tank turn off.

Isaac read a book. 1st day he read 2/5 of it unread. 2nd day he read another 24 page of the book . In the end he read was 5/9the pages did not read. If he finish the rest in 4 days. What was the average number he read for the rest of the book?

[kiasustar]

Mr Dano sold 3 types of durian.3/8 were D24, 40%of the remainder were XO n bal were Segamat. The amt of money earned fr 1j

Kg each type are as follow: D24 $3, XO $4.50 & Segamat $5. The ratio of D24 to XO and Segamat sold on Monday are 4:3:2. In total, he sold 6/7 of the total durians at his stall that day and earned $568. How many Segamat durians did he have at first?

Anyone can help?

:thankyou:

[2DMommy]

tianzhu:

2DMommy:

It was my boy school homework. As the teacher was on MC the last 2 days, we are still unable to solve or check the answer. Will get him to check the question again. Thank you !

Hi

It's an interesting question.

One possible scenario is to assume Mr Lim taking 25 minutes to return home at 9am.In this case, the distance of 16 km is between Mrs Lim and the house after a period of 50 minutes.

Best wishes

Hi Tianzhu

Indeed there's an error in this question. It should be :

Mr and Mrs Lim travelled in opposite directions after leaving their house at the same time. Mr Lim travelled towards Ponggol while Mrs Lim travelled towards Jalan Elias. Mrs Lim drove at a speed which was 12km/h slower than Mr Lim. After 25 min, Mr Lim had to turn back towards home for his misplaced keys while Mrs Lim continued with her journey to Jalan Elias without stopping. At 8am the distance between Mr and Mrs Lim was 16 km. How far was Mrs Lim from her home at 9am?

[MathIzzzFun]

kiasustar:

Mr Dano sold 3 types of durian.3/8 were D24, 40%of the remainder were XO n bal were Segamat. The amt of money earned fr 1j

Kg each type are as follow: D24 $3, XO $4.50 & Segamat $5. The ratio of D24 to XO and Segamat sold on Monday are 4:3:2. In total, he sold 6/7 of the total durians at his stall that day and earned $568. How many Segamat durians did he have at first?

Anyone can help?

:thankyou:

Hi

at first:
D24: XO : Segamat --> 3 : 2 : 3 --- total 8


Durian sold on Monday:
D24: XO : Segamat --> 4:3:2 --- total 9

Consider every group of 9 durians sold,
Total amount earned
= 4 x $3 (D24) + 3 x $4.50 (XO) + 2 x $5 (Segamat)
= $35.50

Number of groups sold --> $568 ÷ $35.50 = 16
Total number of durians sold --> 16 x 9 = 144

Number of durians at first --> 7/6 x 144 = 168
Number of Segamat durians, at first --> 3/8 x 168 = 63

cheers.