Q&A - PSLE Math

[tianzhu]

Emelyn:

Many Thanks.... Tianzhu. You are the saviour.

Solution from my son's teacher.....

7-Up = 135
Ice-lemon Tea = 60
Difference is 75
% more => 25%

Err..... I am starting to worry.... why is she solving both problems using the differences ?

Hi Emelyn

You're welcome.

Let’s take an example where many of us are familiar with, wage increment.

For example, if a company recommends an increase of 5% in the salary of a worker. This means for every $100 in the original salary, there is an increase of $5.

Pretend that the original salary is $1800, then the new salary will be 105/100*1800 which is $1890.

Now let us go back to the question on pie chart.

Let’s work out the number of cans for easy comparison.

% of 7 up canned drinks ------ 45% ------- 135
% of ice lemon tea canned drinks ------- 20% -------- 60

135 – 60 ------ 75

In this case, 60 cans is the base or 100%
75/60* 100% --------125%

If you do a quick check,135 is slightly above twice the amount of 65, therefore 25% is offside.

Best wishes

[chl72]

Hi! Please help…


Darren saves $1.40 and Sonia saves $1.10 more than him daily. Although Sonia started saving 1 weeek later than Darren, she has now saved $2.30 more than him. How many days has Darren been saving?

Tia!

[tianzhu]

chl72:

Darren saves $1.40 and Sonia saves $1.10 more than him daily. Although Sonia started saving 1 weeek later than Darren, she has now saved $2.30 more than him. How many days has Darren been saving?

Hi

I would like to share some thoughts which I hope would help.

In 1 week or 7 days, Darren saved ------- 7 x 1.4 ------- 9.8

9.8 + 2.3 ------- 12.1 or 1210 cents

Sonia saved $1.1 or 110 cents more than Darren.

Sonia saved for (1210/110) ------ 11 days.

Darren saved for (11 + 7) ------ 18 days

Best wishes

[chl72]

tianzhu:

chl72:

Darren saves $1.40 and Sonia saves $1.10 more than him daily. Although Sonia started saving 1 weeek later than Darren, she has now saved $2.30 more than him. How many days has Darren been saving?

Hi

I would like to share some thoughts which I hope would help.

In 1 week or 7 days, Darren saved ------- 7 x 1.4 ------- 9.8

9.8 + 2.3 ------- 12.1 or 1210 cents

Sonia saved $1.1 or 110 cents more than Darren.

Sonia saved for (1210/110) ------ 11 days.

Darren saved for (11 + 7) ------ 18 days

Best wishes

Thank you very much Tianzhu!

[bobsg01]

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Need help to check on this answer:

Ruler = $20
No of Rulers = 20 / 0.40 = 50
No of Erasers = 50 / 2 = 25
Eraser Amount = 25 * 0.70 = $17.50
Rulers and Erasers = 20 + 17.50 = $37.50

Fraction 5/8 spent on pens
Fraction (the rest) = 8/8 - 5/8 = 3/8
Per unit of Rulers and Erasers = 37.50 / 3 = $12.50

Hence, total spend on Pens = 12.50 * 5 = $62.50

Can someone help to see if the calculation is correct.

Thanks in Advance for anyone who help.

[tianzhu]

chl72:

Thank you very much Tianzhu!

Hi

You're welcome.

Best wishes

[tianzhu]

Hi bobsg01


Your answer is correct.

Best wishes

[bobsg01]

Thanks for your verification Tianzhu.


Now I can confirm that the answer provided $17.50 was wrong.

[tianzhu]

bobsg01:

Thanks for your verification Tianzhu.


Now I can confirm that the answer provided $17.50 was wrong.

Hi

You're welcome.

Best wishes

[tianzhu]

Hi


In this question, a student should note that the number of apples and oranges remains the same in both scenarios.

A student who is familiar with SE could proceed to use it. If not, he/she could solve it using the alphabet method or pictorially.

In this illustration, I’ve done it pictorially. As usual, I’ve put in more details than necessary because I wanted to show the flow of events. Once you understand the concept, you may express the solution in your own way.

Best wishes.

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