Q&A - PSLE Math

[whitety]

Hi, Need help on 2 qns:


Q1. Mrs Devi and Mrs Singh made a total of 675 pies. After selling some pies each, the number of pies Mrs Devi had left was 4 times the number of pies she sold and the number of pies Mrs Singh had left was thrice the number of pies she sold. Given that both of them had a total of 531 pies left, how many pies did Mrs Devi have at first ?

Q2. 2/3 of the number of Jacob’s trading cards was equal to 1/4 the number of Samy’s trading cards. After each of them bought 52 trading cards, Samy ended up with twice as many trading cards as Jacob. How many trading cards did Samy have at first ?

Thanks!

[MathIzzzFun]

whitety:

Hi, Need help on 2 qns:


Q1. Mrs Devi and Mrs Singh made a total of 675 pies. After selling some pies each, the number of pies Mrs Devi had left was 4 times the number of pies she sold and the number of pies Mrs Singh had left was thrice the number of pies she sold. Given that both of them had a total of 531 pies left, how many pies did Mrs Devi have at first ?


Thanks!

Hi

Q1..

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cheers.

[MathIzzzFun]

whitety:

Hi, Need help on 2 qns:



Q2. 2/3 of the number of Jacob's trading cards was equal to 1/4 the number of Samy's trading cards. After each of them bought 52 trading cards, Samy ended up with twice as many trading cards as Jacob. How many trading cards did Samy have at first ?

Thanks!

Hi

2/3 Jacob = 1/4 Samy
2/3 Jacob = 2/8 Samy

Jacob's cards --> 3 units } difference = 5 units
Samy's cards --> 8 units }

Each bought 52 tradings cards --> difference remain the same.
after the purchase
Jacob's cards --> 5 units
Samy's cards --> 10 units

2 units --> 52
1 unit --> 26

Samy's cards at first --> 8 x 26 = 208

cheers.

[whitety]

Hi MathIzzzFun,


Thank you very much for your help!

[Spongy]

Hi, pls help. Thank you!


1. In 320, 3>2>0, that is, the digits in the hundreds place, tens place and ones place are in decreasing order. How many such 3-digit numbers are there?

2. Mark has a bag of sweets. He repacks 3/4 of them into small packets of 15 sweets each and the rest into large packets of 25 sweets each. Find the ratio of the number of large packets to the number of small packets.

[tianzhu]

Spongy:

Hi, pls help. Thank you!

1. In 320, 3>2>0, that is, the digits in the hundreds place, tens place and ones place are in decreasing order. How many such 3-digit numbers are there?

Hi

First thing first, is such a question within the PSLE syllabus?

Where is your question from?

Most probably, PSLE students would think of \"Systematic Listing\" as this a a strategy covered in the syllabus.However, it's tedious.

Please check with your school teacher if it is within the syallabus.

The answer is 120.

Best wishes

[tianzhu]

Spongy:

2. Mark has a bag of sweets. He repacks 3/4 of them into small packets of 15 sweets each and the rest into large packets of 25 sweets each. Find the ratio of the number of large packets to the number of small packets.

Hi

You may present in MD or “Number*Value” format.

Large ------ 1*25 ------ 25

Small ------ 3*25 ------ 75

Large packets:Small packets------- 1:5

Best wishes

[MathIzzzFun]

Spongy:

Hi, pls help. Thank you!


2. Mark has a bag of sweets. He repacks 3/4 of them into small packets of 15 sweets each and the rest into large packets of 25 sweets each. Find the ratio of the number of large packets to the number of small packets.

Hi

Total number of sweets in LARGE packets : SMALL packets
= 1 : 3
= 25 : 75
= 25 x 1 : 15 x 5

Ratio of number of LARGE packets : SMALL packets
= 1 : 5

cheers.

[Spongy]

Hi, I am not very sure if it is in the school syllabus. This question is from an assessment book. Thanks for solving the questions for me.

[kiasuaunt]

speedmaths.com:

kiasuaunt:

Car A left Singapore for Penang. Car B left Penang for Singapore at the same time using the same route. 3 hrs after the two cars had set off, they were 760 km apart. 5 hrs after they had set off, the distance between the two cars was 400 km. How many hrs after setting off would the two cars meet?


Thanks.

Hi,

The cars took 5 - 3 = 2 hours to close up 760 - 400 = 360 km.
The cars took 2 hours to close up 360 km.
The cars will take another 400/360 x 2 = 2 2/9 hours to close up the last 400 km.

5 + 2 2/9 = 7 2/9 hours.

Hope this helps.

Cheers


speedmaths.com

Thank you but still trying to figure this out: The cars will take another 400/300 x 2 to close up the last 400 km.