But sadly, these questions have appeared in PSLE's and prelim's papers before, and sad to say, Mr Fong finds them difficult too! *shy shyyyyy*
"There are some marbles in Box A and Box B. If 50 marbles from Box A and 25 from Box B are removed each time, there will be 600 marbles left in Box A when all marbles are removed from Box B. If 25 marbles from Box A and 50 marbles from Box B are removed each time, there will be 1800 marbles left in Box A when all marbles are removed from Box B. How many marbles are there in each box?"
Wah so long, can sweat liao leh... This one is a 5-mark question, I know it
is difficult but don't think Mr Fong lost his marbles ok.. (must stop the
puns,quick!!! :P)
I suspect the one that asked question must be a child, so many marbles..Haha, Mr Fong no class today, feel very lame la.
This question might be MOE's way of taking revenge against the potential Archimedes who can do normal PSLE papers as easily as how they dig nose!
By any means, let me give you people a clue: remember to find the link between box A and B!
If you do find the link, this question is so easy already...See, Mr Fong never 'pray pray' with you! :D
This question is much longer than the previous question, so you can just explain and give your answers without the workings if you know how to do them! If you know how to do the addition questions, you can try them too. Enjoy! :)
Stumble It!
11 comments:
waa...so hard ah
i can do it actually but i aint tellin u
Mr. Fong,
I would like to sincerely express my apologies as i do not see any maths problems throughout your blog.
REALLY sincerely,
Mr. Wong Bungijumper
answers, 1: 65
2: -40
Jet: Don't know then say don't know ah! :)
Hope to see your working soon!
anonymous: Thanks for trying! :D may i know how you got your answers?
box b 800 box a 2200
OMG i'M too smart lah
kevvvvv: Your name so many v's! Haha yes,CORRECT! :)))))
i presume you did it by trial and error? :)
let's say the boxes are full now.
#1: if i removed 600 from A now, the ratio of A:B is 2:1
#2: if i removed 1800 from A now, the ratio of A:B is 1:2
therefore, draw diagram of both scenario:
#1: A:OO
B:O
#2: A:O
B:O
do realise that the O represent one box. but each box are different representations.
Now, think. B in both scenarios are the SAME number! 'cos i did not remove anything from B in both scenario. therefore, 2 OO in #1 represents 1 O in #2 of B.
THINK...
Ok, therefore, the new diagrams are
#1: A OOOO
B OO
#2: A O
B OO
now, theses O means the same number each.
ok, solution: A in #1 substract A in #@ is 3 OOO. which is 1800-600
therefore 1 O is 400.
ok, final answer
A:400+1800 = 2200
B:400x2 = 800
ok, done.
This is primary school solution for primary school maths...
no challenge..
Jerry: EXCELLENT.phenomenal :)
Another Easy one!
Let box A have A marbles, and box B, B marbles.
1st case, -50 from A and -25 from B until B reaches 0:
Thus, -50 is applied x times to A, and -25 is applied x times to B. Remainder is 600 for A, 0 for B.
So construct an equation:
A = 50 * x +600
B = 25 * x
2nd case, 25 is taken from A, and 50 from B until B reaches 0:
Thus, -25 is applied to A, y times. And -50 to B, y times. Leaving A with 1800, and B with 0.
So construct a second pair of equations:
A = 25 * y + 1800
B = 50 * y
Now, combining:
25 * x = 50 * y
therefore, x = 2y
50x + 600 = 1800 + 25y
50x = 1200 + 25y
2x = 48 + y
substitute x = 2y,
4y = 48 + y,
3y = 48,
y = 16
Thus box A has:
16 * 25 + 1800 = 2200 marbles
Box B has:
16 * 50 = 800 marbles
Levy XD: AHHH, are you from the University of the #@$#@$ College and majoring in Maths? :O
I feel emulated.Lol!
Thank you so much,you smart PhD holder! But remember, we are talking PSLE here eh.. :)
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