Q&A - PSLE Math
-
abc_parent:
Q12) Tank P was filled with water as shown in the diagram (pls help with this if you have the diagram). Water was then poured from Tank P to Tank Q until the height of the water level in Tank P became twice that of the water level in Tank Q. Find the volume of water in Tank Q. Given your answers in litres.
http://www.orlesson.org/orp/09Ma/2009-P6-Math-SA2-HenryPark.pdf
Suggested solution
Original volume of water in tank P = 55cmx40cmx30cm = 66000 cm³
Assume the height of water in Tank Q be h,
New volume of water in tank P = 2h cmx40cmx30cm=2400h cm³
New volume of water in tank Q = h cmx100cmx20cm = 2000h cm³
2400h + 2000h = 66000
4400h = 66000
h = 15
New volume of water in Tank Q = 15cmx100cmx20cm = 30000 cm³ = 30 litres.
Volume of water in Tank Q = 30 litres.
PS: If there is given answer, pls state it together with the question. Does not matter if it's 100% or not, the given answer is for reference purpose. -
Vanilla Cake:
Hi VC,Hi Uncle Tianzhu / Uncle Dharma,
Could you pls spare time to look into part (b) of http://psle2010a.blogspot.com/2010/09/volume-p6-2010-maha-bodhi-p2-q13.html and express your comments.The answer given for (b) is 56.25
Thanks.
Definately there is lack of info from what I read from the qn in Observer's blog. I don't have the actual papers to check the actual wordings on the qn. -
Vanilla Cake:
Hi VCHi Uncle Tianzhu / Uncle Dharma,
Could you pls spare time to look into part (b) of http://psle2010a.blogspot.com/2010/09/volume-p6-2010-maha-bodhi-p2-q13.html and express your comments.The answer given for (b) is 56.25
Thanks.
There may be some missing information.
Best wishes -
Maha Bodhi P6 Prelim 2010: Paper 2: Q16. Tom and Jerry shared a box of marbles. If Tom was given 10 fewer marbles, Jerry would have five times as many marbles as Tom. If Tom was given 10 more marbles, he would have ½ as many marbles as Jerry. What percentage of the marbles did Tom receive? [5 marks][Answer given: 25%]
Hi VC
Have you tried this question?
Could you get the same answer as given in the WS?
You may use MD.
Before
Tom -------1u+10
Jerry -------5 units
After
Tom ------- 1u+10+10
Jerry ------- 2units+40
3 units ------40
1unit ------40/3
Tom ------- 40/3+10 ----- 70/3
Jerry -------200/3
Total number of marbles ------- 200/3+70/3 --------90
Tom/Total ---------70/3/90*100 ------- 25 25/27% (25 and 25/27%)
Best wishes -
tianzhu:
Dear Uncle Tianzhu,Maha Bodhi P6 Prelim 2010: Paper 2: Q16. Tom and Jerry shared a box of marbles. If Tom was given 10 fewer marbles, Jerry would have five times as many marbles as Tom. If Tom was given 10 more marbles, he would have ½ as many marbles as Jerry. What percentage of the marbles did Tom receive? [5 marks][Answer given: 25%]
Hi VC
Have you tried this question?
Could you get the same answer as given in the WS?
You may use MD.
Before
Tom -------1u+10
Jerry -------5 units
After
Tom ------- 1u+10+10
Jerry ------- 2units+40
3 units ------40
1unit ------40/3
Tom ------- 40/3+10 ----- 70/3
Jerry -------200/3
Total number of marbles ------- 200/3+70/3 --------90
Tom/Total ---------70/3/90*100 ------- 25 25/27% (25 and 25/27%)
Best wishes
Sorry for the late reply as I had accompanied my mum to the wet market, this morning.Thanks for highlighting and after reading your post, I went to look at my calculations again and also went to http://psle2010a.blogspot.com/2010/09/maha-bodhi-p6-prelim-2010-paper-2-q16.html.
Both of you got 25 and 25/27%. It's the way of interpretation of the question that matters. My one is different from both of you and pls don't laugh at me (just joking) if I am wrong. Using unit and part method that Uncle Dharma usually uses, pls correct me along the way:
Case 1
T = u+10
J = 5u-10
Case 2
T = p-10
J = 2p+10
2p+10=5u-10
2p =5u-20
p = 2.5u-10
u+10=p-10
u+10=2.5u-20
30=1.5u
u=20
p=40
T = u+10 = 20+10 = 30 or p-10 = 40-10=30
J = 5u-10 = 5(20)-10 =90 or 2p+10 = 2(40)+10 = 90
Total of T + J = 30+90=120
Percentage of the marbles received by Tom =30/120x100% = 25% -
Vanilla Cake:
Dear Uncle Tianzhu,tianzhu:
Maha Bodhi P6 Prelim 2010: Paper 2: Q16. Tom and Jerry shared a box of marbles. If Tom was given 10 fewer marbles, Jerry would have five times as many marbles as Tom. If Tom was given 10 more marbles, he would have ½ as many marbles as Jerry. What percentage of the marbles did Tom receive? [5 marks][Answer given: 25%]
Hi VC
Have you tried this question?
Could you get the same answer as given in the WS?
You may use MD.
Before
Tom -------1u+10
Jerry -------5 units
After
Tom ------- 1u+10+10
Jerry ------- 2units+40
3 units ------40
1unit ------40/3
Tom ------- 40/3+10 ----- 70/3
Jerry -------200/3
Total number of marbles ------- 200/3+70/3 --------90
Tom/Total ---------70/3/90*100 ------- 25 25/27% (25 and 25/27%)
Best wishes
Sorry for the late reply as I had accompanied my mum to the wet market, this morning.Thanks for highlighting and after reading your post, I went to look at my calculations again and also went to http://psle2010a.blogspot.com/2010/09/maha-bodhi-p6-prelim-2010-paper-2-q16.html.
Both of you got 25 and 25/27%. It's the way of interpretation of the question that matters. My one is different from both of you and pls don't laugh at me (just joking) if I am wrong. Using unit and part method that Uncle Dharma usually uses, pls correct me along the way:
Case 1
T = u+10
J = 5u-10
Case 2
T = p-10
J = 2p+10
2p+10=5u-10
2p =5u-20
p = 2.5u-10
u+10=p-10
u+10=2.5u-20
30=1.5u
u=20
p=40
T = u+10 = 20+10 = 30 or p-10 = 40-10=30
J = 5u-10 = 5(20)-10 =90 or 2p+10 = 2(40)+10 = 90
Total of T + J = 30+90=120
Percentage of the marbles received by Tom =30/120x100% = 25%
Can also using units(u) only
After 1st condition
Tom:1u
Jerry:5u
Reinstate to original position
Tom:1u+10
Jerry:5u-10
2nd condition using original position data
..........................................ratio
Tom:1u+10+10=1u+20--------1
Jerry:5u-10-10=5u-20----------2
===>2u+40=5u-20
.........3u=60
.........1u=20
Tom has 1x20+10=30
Jerry has 5x20-10=90
Total=30+90=120
Percentage=30/120x100=25% -
tianzhu:
Alternatively, you can use algebra.Maha Bodhi P6 Prelim 2010: Paper 2: Q16. Tom and Jerry shared a box of marbles. If Tom was given 10 fewer marbles, Jerry would have five times as many marbles as Tom. If Tom was given 10 more marbles, he would have ½ as many marbles as Jerry. What percentage of the marbles did Tom receive? [5 marks][Answer given: 25%]
Hi VC
Have you tried this question?
Could you get the same answer as given in the WS?
You may use MD.
Before
Tom -------1u+10
Jerry -------5 units
After
Tom ------- 1u+10+10
Jerry ------- 2units+40
3 units ------40
1unit ------40/3
Tom ------- 40/3+10 ----- 70/3
Jerry -------200/3
Total number of marbles ------- 200/3+70/3 --------90
Tom/Total ---------70/3/90*100 ------- 25 25/27% (25 and 25/27%)
Best wishes
---------------------------------------------------------------------------------
Let t and j represent the number of marbles Tom and Jerry received respectively.
j+10=5*(t-10)
=5t-50
-----------------------
Therefore, we have statement 1:
j=5t-60
-----------------------
t+10=(j-10) * 1/2
t+10=j/2 - 10/2
t+10=j/2 - 5
----------------------
Statement 2:
t=j/2-15
----------------------
Since we know what 't' is in terms of j,
Therefore we can replace the 't' in statement 1
in terms of 'j'.
We have:
j=5(j/2-15)-60
j= 5j/2 - 75-60
j=5j/2 - 135
---------------------
We bring all numbers to one side of the equation:
5j/2 - j = 135
Get rid of the '/2' by multiplying BOTH sides of the equation by 2:
5j-2j=270
3j=270
j=90
If Tom was given 10 fewer marbles, Jerry would have five times as many marbles as Tom.
j+10=5(t-10)
100=5(t-10)
t=30
30/(90+30)=30/120=25%
Note: the PSLE teachers are known to be stingy and MAY penalize you for this: 30/120=25%
The safest way is: (30*100%)/(120*100%)=25% -
Vanilla Cake:
Hi VC
Sorry for the late reply as I had accompanied my mum to the wet market, this morning.Thanks for highlighting and after reading your post, I went to look at my calculations again and also went to http://psle2010a.blogspot.com/2010/09/maha-bodhi-p6-prelim-2010-paper-2-q16.html.
Both of you got 25 and 25/27%. It's the way of interpretation of the question that matters. My one is different from both of you and pls don't laugh at me (just joking) if I am wrong.
I think your mother is training you to be a good wife in the future.
There is always more than one ways of looking at a question. How one interprets the question can sometimes lead to different answers.
One of the challenges faced by students is guessing correctly what the question setter wanted them to do.
Yes, how you interpret the question is logical.The key word here is shared.
I am sorry for making the mistake.
Best wishes -
Hi,
Please help with this question,
Ailing, Bala, Chris and Dawn shared the cost of a gift for their friend. Ailing paid 1/5 of the amt paid by Bala, Chris and Dawn. Chris paid 40% of the amt paid by Ailing and Bala. The total amt paid by Ailing and Bala is equal to that paid by Chris and Dawn. Given that Dawn paid $32 more than Ailing for the gift, what was the cost of the gift?
Thank you![/list] -
Hi,
Please help with this question,
Ailing, Bala, Chris and Dawn shared the cost of a gift for their friend. Ailing paid 1/5 of the amt paid by Bala, Chris and Dawn. Chris paid 40% of the amt paid by Ailing and Bala. The total amt paid by Ailing and Bala is equal to that paid by Chris and Dawn. Given that Dawn paid $32 more than Ailing for the gift, what was the cost of the gift?
Thank you![/list]
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login