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Saturday, June 24 2017 @ 05:22 AM CDT
 Forum Index >  Test Paper Related >  Primary 4 Matters
 Challenging Math Question.
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By: Johny123 (offline)  Saturday, September 25 2010 @ 08:18 AM CDT (Read 2771 times)  
Johny123

Sally baked some cookies to sell. 3/4 of them were chocolate cookies and the remaining were almond cookies. After she sold 5/6 of chocolate cookies and 210 almond cookies, she had 1/5 of the cookies left. How many cookies did she sell?
My ans : 1200 cookies.
Other Website Ans: 960 cookies.

Can you tell me which of the two answers are correct and if its 960 cookies, why ?

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By: kellywww (offline)  Monday, September 27 2010 @ 02:07 AM CDT  
kellywww

Is this a P4 math question?

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By: tanhuimin (offline)  Tuesday, September 28 2010 @ 04:47 AM CDT  
tanhuimin

This is a bit challenging for P4, should be able to solve via Model drawing

Yes, answer should be 1200.
we can work backward to check the answer
check if the answer is 960,
no. of chocolate = 720, chocolate sold = 600, total sold = 600 + 210 = 810 --> 810/960 not = 4/5, so answer is definitely not 960.
check if the answer is 1200,
no. of chocolate = 900, chocolate sold = 750, total sold = 750 + 210 = 960 --> 960/1200 = 4/5 Bingo!

I have tried using what a P4 has learnt to solve the problem,
Pls refer to model diagram.

Thanks

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By: acelow (offline)  Friday, October 01 2010 @ 01:02 AM CDT  
acelow

c = 3a (3 times of almond)

cx 5/6 + 210 = (c + a) x 4/5
3a x 5/6 + 210 = (3a + a) x 4/5
2.5a + 210 = 3.2a
210 = 3.2a-2.5a = 0.7a
a = 0.7 / 210 = 300

c=300x3=900
Sold = 900x5/6 + 210
750+210 = 960

A difficult question! Eek!

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By: suz855 (offline)  Sunday, October 03 2010 @ 11:39 PM CDT  
suz855

Before
chocolate = 6u
almond = 2u

After
1/5 --> 3u-210 ---- (1)
4/5 --> 5u+210 --- (2)

(1) x4 12u-840=5u+210
7u =1050, 1u=150

At first (8u) ---> 8 x 150 = 1200

Big Grin

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By: erne (offline)  Wednesday, October 13 2010 @ 02:52 AM CDT  
erne

the question is :How many cookies did she sell?
So the Answer should be 1200x4/5=960

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By: kellywww (offline)  Sunday, October 17 2010 @ 12:40 AM CDT  
kellywww

if i am not wrong, it's a P6 math question.

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By: sethchew (offline)  Friday, October 22 2010 @ 08:52 PM CDT  
sethchew

Quote by: Johny123

Sally baked some cookies to sell. 3/4 of them were chocolate cookies and the remaining were almond cookies. After she sold 5/6 of chocolate cookies and 210 almond cookies, she had 1/5 of the cookies left. How many cookies did she sell?
My ans : 1200 cookies.
Other Website Ans: 960 cookies.

Can you tell me which of the two answers are correct and if its 960 cookies, why ?


well.......
3/4 x 1/6 = 1/8
1/5 - 1/8 = 3/40
210/3 = 70
70 x 40 = 2800
2800 x 4/5 = 2240
i'm sure its correct.
Look Checking:
2800 - 2240 = 560
if its correct, it should be 1/5th
560 x 5 = 2800
am i correct??

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By: sethchew (offline)  Friday, October 22 2010 @ 09:00 PM CDT  
sethchew

Quote by: acelow

c = 3a (3 times of almond)

cx 5/6 + 210 = (c + a) x 4/5
3a x 5/6 + 210 = (3a + a) x 4/5
2.5a + 210 = 3.2a
210 = 3.2a-2.5a = 0.7a
a = 0.7 / 210 = 300

c=300x3=900
Sold = 900x5/6 + 210
750+210 = 960

A difficult question! Eek!



acelow please look at my answer.
if you do not, check:
960(in your opinion) should be 4/5
960/4= 240 240x5= 1200
are you sure its correct?

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