Q&A - P5 Math
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Chan09:
HiCouldn't figure this one: what is the greatest number of right angles that a 5 sided figure can have? Ans: 4
I couldn't draw the figure? Thanks
Just throwing up some thoughts, I am not sure if we can count the right angles formed by adjacent perpendicular lines.
Best wishes.
http://farm7.static.flickr.com/6188/6108205460_6cbc7a4bc7_z.jpg\"> -
Hi. Just my thoughts below:
Sum of interior angles of n-sided polygon is (n-2) x 180 degrees
so sum of interior angles of 5-sided figure = (5-2) x 180 = 540 degrees
If max no. of right angles is 4, that will mean the remaining last angle is
540 - 4x90 = 180 degrees
That’s only possible if you allow for collinear vertices, ie vertices that lie in
same straight line. But that will mean a 4-sided figure is the same as a 5-sided figure.
Else if no collinear vertices allowed, would think max no. of right angles is 3. -
Tks as felt question was a bit misleading.
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Pail A contained 7/17 of the amount of water in Pail B. Pail C contained 1/9 of the total amount of water the three pails had. If Pail A and Pail B contained 5.25 litres of water more than Pail C, how much water did Pail B contain? (give the answer in litres)
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Jcong:
Pail A contained 7/17 of the amount of water in Pail B. Pail C contained 1/9 of the total amount of water the three pails had. If Pail A and Pail B contained 5.25 litres of water more than Pail C, how much water did Pail B contain? (give the answer in litres)
Hi
Pail A ----- 7 units
Pail B ----- 17 units
Multiples of 9 ------- 9, 18,27 ………
1/9*27 -----3 units
Pail C ------ 3 units.
24units – 3 units ------ 21units
21units ----- 5.25
1unit ----- 0.25
Pail B -----17*0.25 ------- 4.25
Best wishes -
Why do you use multiple of 9? and why is 27 chosen instead of other numbers like 18? So sorry don’t really understand. Thanks
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Jcong:
Why do you use multiple of 9? and why is 27 chosen instead of other numbers like 18? So sorry don't really understand. Thanks
Hi
C contained 1/9 of the total amount of water the three pails had.
Hence, we use multiples of 9, just to make the calculations easier.
The number of units for Pail A and Pail B add up to 24(7+17).
Hence the total number of units(A+B+C) has to be greater than 24.
Alternatively, you may use MD.
7units (Pail A) +17units (Pail B) + 1part (Pail C) ------- 9 parts (representing A+B+C)
24units ------- 8parts
3units ------- 1part.
Best wishes -
Thank you so much. Now I understand.
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Jcong:
Thank you so much. Now I understand.
Hi
Good Morning.
You’re welcome.
Best wishes -
Hi all, please help me the following:
Source : 2010 RGPS P5 SA2
http://orlesson.com/10Ma/2010-P5-Math-SA2-RGPS.pdf
Paper 1, Question 28.
Paper 1, Question 29.
Paper 2, Question 12. Part (a) My answer is $319.50 which is different from answer key.
Paper 2, Question 17.
Thanks in advance.