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March 28, 2024, 07:49:19 pm

Author Topic: 3U Maths Question Thread  (Read 1230142 times)  Share 

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imtrying

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Re: 3U Maths Question Thread
« Reply #180 on: June 06, 2016, 05:28:48 pm »
0
Hey:)
I'm struggling a bit with the attached question from the Binomial Theorem topic, wondering if I could have a hand?
Thanks so much  8)
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RuiAce

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Re: 3U Maths Question Thread
« Reply #181 on: June 06, 2016, 05:35:21 pm »
+2
Hey:)
I'm struggling a bit with the attached question from the Binomial Theorem topic, wondering if I could have a hand?
Thanks so much  8)

(Aka. the definition of the combinatoric operator)




Such a question would not be asked in the exam except for as multiple choice as the final answer is too ambiguous
« Last Edit: June 06, 2016, 05:38:29 pm by RuiAce »

katherine123

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Re: 3U Maths Question Thread
« Reply #182 on: June 08, 2016, 03:14:14 pm »
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i dont get part (iii) for question 1

ques2 : the answer is 35/72

jakesilove

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Re: 3U Maths Question Thread
« Reply #183 on: June 08, 2016, 04:18:20 pm »
+2
i dont get part (iii) for question 1

ques2 : the answer is 35/72

Hey! I'll just quickly answer your second question: honestly, I'll leave the first to someone who can use LaTex better than me.

To draw a Blue ball from the first bag, there is a chance. To draw a Blue ball from the second bag, there is a . So, to get the probability of picking two blue balls, we just multiple these together! The answer will be as you told us! You can answer the other questions in a similar fashion: The probability of getting one yellow and one blue ball will be the probability of getting a yellow THEN a blue plus the probability of getting a blue THEN a red. The probability of getting at least one yellow ball will be the probability of getting a red and a yellow plus the probability of getting two yellows (or, more easily, 1 minus the probability of getting two blues!).

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RuiAce

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Re: 3U Maths Question Thread
« Reply #184 on: June 08, 2016, 06:54:54 pm »
+4
i dont get part (iii) for question 1

ques2 : the answer is 35/72













« Last Edit: September 16, 2017, 11:44:43 am by RuiAce »

jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #185 on: June 08, 2016, 10:45:11 pm »
+3


I distinctly remember doing this question in the lead up to my Extension 1 exam, it was nasty, very grateful to have not seen this question under pressure  :o

RuiAce

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Re: 3U Maths Question Thread
« Reply #186 on: June 09, 2016, 07:31:59 am »
+1
I distinctly remember doing this question in the lead up to my Extension 1 exam, it was nasty, very grateful to have not seen this question under pressure  :o

Back when I was studying for Ext 1 I couldn't get it out :P

katherine123

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Re: 3U Maths Question Thread
« Reply #187 on: June 10, 2016, 06:12:57 pm »
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how to do this question ?
the region in the first quadrant bounded by x=y-y^3, x=1, y=1 is rotated about y axis. Find the  volume of solid generated

RuiAce

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Re: 3U Maths Question Thread
« Reply #188 on: June 10, 2016, 07:38:40 pm »
+1
how to do this question ?
the region in the first quadrant bounded by x=y-y^3, x=1, y=1 is rotated about y axis. Find the  volume of solid generated







Note: If the curve was what was confusing, notice a trick for this question. (This trick is a bit of a coincidence because of how neat the question is.)
Because the region is bounded by x=1 AND y=1, we could just use the inverse relation y=x-x3 and rotate this region about the x-axis instead.
We get the same integral:


amandali

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Re: 3U Maths Question Thread
« Reply #189 on: June 10, 2016, 09:58:43 pm »
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need help with part c) 

RuiAce

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Re: 3U Maths Question Thread
« Reply #190 on: June 10, 2016, 10:32:59 pm »
+2
(Image removed from quote.)

need help with part c)





I'll leave the rest to you. Basically put this value for t back into the equation for M.

This working out is subject to some inaccuracy

amandali

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Re: 3U Maths Question Thread
« Reply #191 on: June 11, 2016, 11:11:39 am »
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need help with this ques thanks

RuiAce

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Re: 3U Maths Question Thread
« Reply #192 on: June 11, 2016, 11:54:11 am »
+1
(Image removed from quote.)

need help with this ques thanks







Additional note: If you test for various odd values of n (that is, physically expanding it), you will find that indeed there IS no term involving xn.
« Last Edit: June 11, 2016, 11:56:41 am by RuiAce »

katherine123

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Re: 3U Maths Question Thread
« Reply #193 on: June 11, 2016, 09:45:06 pm »
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how to do part b)  and c)
ans for b = 101/144  and ans for c =0.113)


for part c)
what i did was 20C12*(5/8)^12*(3/8)^8 + 20C12*(7/9)^12*(2/9)^8

jamonwindeyer

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Re: 3U Maths Question Thread
« Reply #194 on: June 11, 2016, 10:42:12 pm »
+1
how to do part b)  and c)
ans for b = 101/144  and ans for c =0.113)


for part c)
what i did was 20C12*(5/8)^12*(3/8)^8 + 20C12*(7/9)^12*(2/9)^8

Hey Katherine!! For Part B, it is just the probability of a blue ball from one plus the probability from the other:



We can use this result for Part C. You had the right idea! But the two probabilities are:



These are from Part B. Try Part C with the binomial probability method again with those valuess and the answer should come out!! Let us know if it doesn't and we'll lend a hand  ;D
« Last Edit: June 11, 2016, 10:44:03 pm by jamonwindeyer »