Q&A - PSLE Math

[tianzhu]

vidhyalog:

Hi - Could somebody help me with this sum. From Punggol Primay Prelim 2011.


An egg seller had chicken eggs, duck eggs and quail eggs. He had 225 more quail eggs than duck eggs. After he had sold 60% of the chicken eggs, 2/3 of the duck eggs and 3 times as many quail eggs as duck eggs sold, he found that he had 25% of his quail eggs and a total of 205 eggs left. Find the total number of eggs he had first.

Hi

I’ll just provide some pointers for you to draw the MD.

Draw 3 boxes to show duck.
2 units of duck sold, left 1 unit.
For quail eggs, sold ------- 6 units (3 times), left ------2 units (25% left).

Draw a 5 smaller boxes or circles to show chicken.

From MD, we can see
5 units ----- 225
1 unit ----- 45

Number of eggs left ------ 2 boxes for chickens + 1 unit(duck) + 2 units (quail) ------205

Hence 2 boxes for chicken -----205 – (3*45)
1 box of chicken ------ 35

Total number of eggs he had first. ------ (11*45) + (5*35) -----670

Best wishes

[looking4Tutor]

Thank you, tianzhu.

[tianzhu]

looking4Tutor:

http://i54.tinypic.com/2u6hf1s.jpg\">

Hi

Where is this question from?

Is the answer 38 circular shapes?

Best wishes

[Alchemist]

tianzhu:

vidhyalog:

Hi - Could somebody help me with this sum. From Punggol Primay Prelim 2011.


An egg seller had chicken eggs, duck eggs and quail eggs. He had 225 more quail eggs than duck eggs. After he had sold 60% of the chicken eggs, 2/3 of the duck eggs and 3 times as many quail eggs as duck eggs sold, he found that he had 25% of his quail eggs and a total of 205 eggs left. Find the total number of eggs he had first.

Hi

I’ll just provide some pointers for you to draw the MD.

Draw 3 boxes to show duck.
2 units of duck sold, left 1 unit.
For quail eggs, sold ------- 6 units (3 times), left ------2 units (25% left).

Draw a 5 smaller boxes or circles to show chicken.

From MD, we can see
5 units ----- 225
1 unit ----- 45

Number of eggs left ------ 2 boxes for chickens + 1 unit(duck) + 2 units (quail) ------205

Hence 2 boxes for chicken -----205 – (3*45)
1 box of chicken ------ 35

Total number of eggs he had first. ------ (11*45) + (5*35) -----670

Best wishes

Thank you Tianzhu

[dnsy]

Hi, need help on the following. Thanks in advance!


When a certain number of marbles in a box is divided equally among 5, 16 or 28 boys, there is a remainder of 4 marbles. What is the minimum number of marbles in the box?

[ck123]

tianzhu:

looking4Tutor:

http://i54.tinypic.com/2u6hf1s.jpg\">

Hi

Where is this question from?

Is the answer 38 circular shapes?

Best wishes

Is the answer 36 ?

[MathIzzzFun]

ck123:

tianzhu:

[quote=\"looking4Tutor\"]
http://i54.tinypic.com/2u6hf1s.jpg\">

Hi

Where is this question from?

Is the answer 38 circular shapes?

Best wishes

Is the answer 36 ?[/quote]Hi

tianzhu's answer is correct..

cheers.

[MathIzzzFun]

dnsy:

Hi, need help on the following. Thanks in advance!


When a certain number of marbles in a box is divided equally among 5, 16 or 28 boys, there is a remainder of 4 marbles. What is the minimum number of marbles in the box?

Hi

if we remove 4 marbles, then the remaining number of marbles will be divisible by 5, 16 and 28. So, the number of marbles = LCM of (5,16,28) + 4

cheers.

[dnsy]

Thanks MIZF. Understand it’s the LCM of (5,16,28)+4. But what is the working to derive to the answer, which is 564? If it is via trial and error, it will take a long time. Moreover, this is only a 1 mark question.

[gnagna]

tianzhu:

looking4Tutor:

http://i54.tinypic.com/2u6hf1s.jpg\">

Hi

Where is this question from?

Is the answer 38 circular shapes?

Best wishes

Hi Tianzhu
Can explain how you get 38?