Q&A - PSLE Math

[yeodo]

Hi Parents


Please help with this question :

Luke spent 45% of his monthly income. For the month of July, his income was 30% less than August. His expenses for July was $648 less than his expenses for August. What was his income in August?

[TLK]

ANSWER =$6,240.00

[tianzhu]

yeodo:

Hi Parents


Please help with this question :

Luke spent 45% of his monthly income. For the month of July, his income was 30% less than August. His expenses for July was $648 less than his expenses for August. What was his income in August?

Hi

A quick one, as you may need the solution while preparing for SA2.

We are comparing with the income in August.The income for August is our base (100%).

When income for July decreases by 30%, there is a corresponding decrease in Luke’s spending.

30/100*45% ----- 13.5%
13.5% of his income in August was $648.
Therefore 100% of his income ----- 4800.

Hope this helps.

Best wishes

Check

August
Income ----- 4800
Spending ----- 2160

July
Income ----- 3360
Spending ------ 1512

Therefore difference ------(2160-1512) ------648

[tianzhu]

leesf:

Can you enlighten me on the above? Sorry, I still can't see the pattern from the above. Thanks

Hi leesf

Good Morning,please refer to Dharma's solution which was posted earlier in this thread.

Best wishes

[naggo-nitemare]

Hi, my DS' answer is as follows:


(Expenditure of July):(Expenditure of August)=7:10
10-7=3
$648/3=$216
$216 x 10=$2160

(Expenditure of August):(Income of August)=9:20 (reduced from 45:100)
$2160/9=$240
$240 x 20=$4800

[Dharma]

yeodo:

Hi Parents


Please help with this question :

Luke spent 45% of his monthly income. For the month of July, his income was 30% less than August. His expenses for July was $648 less than his expenses for August. What was his income in August?

0.45 (10u - 7u) = $648
1.35u = $648
Income in Aug = 10u = $6480/1.35 = $4800

[Kiasu Friend]

Hi all,


Could anyone provide the solution for this problem:

Robert cycles to his friend’s house and then returns home by the same route. He always cycles at constant sppeds of 5 km/h when going uphill, 15 km/h when going downhill, and 8 km/h when on level ground. If his total cycling time is 2 hrs 40 minutes, what is the distance he cycles in km?

Thanks a lot for your help.

[tianzhu]

James Ang:

Came across some thinking type questions in sec 1 textbooks that can be solved using model/primary methods.;


1. Jack cycles to his friend's house and then returns home by the same route. He always cycles at 4 km/h when going uphill and, 12 km/h when going downhill, and 6 km/h when on level ground. If his total cycling time is 2h 20mins, what is the distance he cycles in km?

Kiasu Friend:

Robert cycles to his friend's house and then returns home by the same route. He always cycles at constant sppeds of 5 km/h when going uphill, 15 km/h when going downhill, and 8 km/h when on level ground. If his total cycling time is 2 hrs 40 minutes, what is the distance he cycles in km?

Hi

Your question is almost similar to JA's earlier question in this thread except for changes in the name and speeds of cyclist.The duration is also slightly different.

You may wish to check if figures(5,8 and 15) are in order.

Best wishes

[kiasuparents_user]

Hi gurus!


I am unsure of the solutions provided for the above question.


Q15c) It is a question to detect patterns.
Any gurus can help me visualise the patterns? Most most most appreciated! Don’t have the diagram so please help if you can.

100 x 49 = 4900 -> how & why?
4900 + 50 - 4950 - how & why?

Thanks in advance!!

[James Ang]

not sure if my speed problem has been solved, the correct answer is 14km.


Kiasu friend's question may not be correct, the uphill speed is 5km/h, the downhill speed is 15km/h, the possible way to solve is when the level ground speed is 7.5km/h, then the total distance travelled is 20km. What is the source of this question, perhaps I can find out if the question is correct or not. Cheers.

tianzhu:

James Ang:

Came across some thinking type questions in sec 1 textbooks that can be solved using model/primary methods.;

1. Jack cycles to his friend's house and then returns home by the same route. He always cycles at 4 km/h when going uphill and, 12 km/h when going downhill, and 6 km/h when on level ground. If his total cycling time is 2h 20mins, what is the distance he cycles in km?

Kiasu Friend:

Robert cycles to his friend's house and then returns home by the same route. He always cycles at constant sppeds of 5 km/h when going uphill, 15 km/h when going downhill, and 8 km/h when on level ground. If his total cycling time is 2 hrs 40 minutes, what is the distance he cycles in km?

Hi

Your question is almost similar to JA's earlier question in this thread except for changes in the name and speeds of cyclist.The duration is also slightly different.

You may wish to check if figures(5,8 and 15) are in order.

Best wishes