Q&A - P5 Math

[tianzhu]

ftwm:

hi need help in this Q.


1/5 of a rectangular tank measuring 30cm long, 20cm wide and 10cm high was filled with water. The ratio of the volume of the water in the tank to that in a bottle was 4 : 3. When some water was poured out of the bottle into the tank, the ratio of the new volume of water in the tank to that in the bottle was 2 : 1. How much water had been poured out of the bottle?

Tq.

Hi

Amount of water in rectangular tank ------- 30*20*10*1/5 ------1200

At first

Tank ----- 4 units ------- 1200

Bottle ------ 3 units ------ 900

The amount of water remains the same before and after (2100).

In the end

Tank ----- 1400 (2)

Bottle ------ 700 (1)

Volume of water from bottle to tank ------- 200

Best wishes

[Udon]

:?: .....needs help...Thank you.


Q1. Sally bought some fish. 1/5 of all fish bought were guppies. The ratio of the number of goldfish to the number of swordtails is 2 : 1.
The prices of the fish were shown below:

Guppies S$1.20 each
Goldfish S$2.30 each
Swordtails S$1.80 each

She spent $116.80 in total. How many swordtails did she buy?



Q2. A bus left the interchange with some passengers on board. At Bus Stop A, 10 passengers boarded the bus. When it reached Bus Stop B, 3/4 of the passengers alighted. The bus continued its journey and at Bus Stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left Bus Stop C.

How many passengers were on the bus when it left the interchange?

[tianzhu]

bookwormkids:

Question:

Oscar and Mavis have some beads. If Oscar gives Mavis 30 beads, he will have twice as many beads as Mavis. If Mavis gives Oscar 30 beads, the ratio of the number of beads she has to the number of beads Oscar has will be 1 : 5. How many beads doe each of them have at first?

Thanks.

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8172/8035716201_1acb9d5ce0_z.jpg\">

[tianzhu]

Udon:

:?: .....needs help...Thank you.


Q1. Sally bought some fish. 1/5 of all fish bought were guppies. The ratio of the number of goldfish to the number of swordtails is 2 : 1.
The prices of the fish were shown below:

Guppies S$1.20 each
Goldfish S$2.30 each
Swordtails S$1.80 each

She spent $116.80 in total. How many swordtails did she buy?

Hi

You may use “Number*Value” or “Grouping Concept”.

Guppies ------ 3 units (1/5)

Goldfish ------ 8 units

Swordfish ------ 4 units

3u*1.2 ------ 3.6u

8u*2.3 ------ 18.4u

4u*1.8 ------- 7.2u

29.2u ----- 116.8

1u ----- 4

Number of swordfish bought ----- 4*4 ------ 16

Best wishes

[tianzhu]

Udon:

Q2. A bus left the interchange with some passengers on board. At Bus Stop A, 10 passengers boarded the bus. When it reached Bus Stop B, 3/4 of the passengers alighted. The bus continued its journey and at Bus Stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left Bus Stop C.

How many passengers were on the bus when it left the interchange?

Hi

For Q2, use the “Working Backwards “strategy.

It’s useful to have a simple diagram to show the flow of events.

Try it out first.

The answer is 170.

Good night.

Best wishes

[bookwormkids]

tianzhu:

bookwormkids:

Question:

Oscar and Mavis have some beads. If Oscar gives Mavis 30 beads, he will have twice as many beads as Mavis. If Mavis gives Oscar 30 beads, the ratio of the number of beads she has to the number of beads Oscar has will be 1 : 5. How many beads doe each of them have at first?

Thanks.

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8172/8035716201_1acb9d5ce0_z.jpg\">

Hi tianzhu, Thank you very much for your answer.

[Udon]

tianzhu:

Udon:

Q2. A bus left the interchange with some passengers on board. At Bus Stop A, 10 passengers boarded the bus. When it reached Bus Stop B, 3/4 of the passengers alighted. The bus continued its journey and at Bus Stop C, 2/3 of the passengers alighted while 3 passengers boarded the bus. There were 18 passengers on the bus when it left Bus Stop C.

How many passengers were on the bus when it left the interchange?

Hi

For Q2, use the “Working Backwards “strategy.

It’s useful to have a simple diagram to show the flow of events.

Try it out first.

The answer is 170.

Good night.

Best wishes

Thank You...
HAPPY Mid-Autumn festival...:)

[tianzhu]

Hi


I've shown the flow of events in pictorial form.Once students become more familiar, they may do without it.

May you be blessed with joy and good fortune in this mid autumn festival.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8319/8041147483_2d1c6fd602_z.jpg\">

[Udon]

tianzhu:

Hi


I've shown the flow of events in pictorial form.Once students become more familiar, they may do without it.

May you be blessed with joy and good fortune in this mid autumn festival.

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8177/8038337524_c793849025_z.jpg\">

think there was a typo error on ; 180-170 = 10

Thank you v much, so we can use this form for all \"backward\" calculation sum?

[tianzhu]

Udon:

think there was a typo error on ; 180-170 = 10

Thank you v much, so we can use this form for all \"backward\" calculation sum?

Hi

Good Morning.

It should be read as 180 - 10 ----- 170.

I've revised the solution.

Best wishes