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# 1)60% people have diabetes, and 56% have insomnia. None have

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1)60% people have diabetes, and 56% have insomnia. None have [#permalink]

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22 Apr 2008, 22:35
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

1)60% people have diabetes, and 56% have insomnia. None have neither. What is the probabaility that a person with insomnia has no diabetes.

2) A has 4 prime factors. B has 3 prime factors. 15 is a common factor to A and B . How many prime factors does AB have.

3) An ellipse is inscribed in a rectangle . The area of an ellipse is given by 1/2 * pi* a * b , where a is the length of the minor axis , and b the major axis. What is the area of the ellipse .

1) Length of the rectangle is 12

2) Breadth of the rectangle is 24.
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22 Apr 2008, 22:46
1) 40/56?

56+60-100 = inso + diab
therfore 40 only inso , 44 only diab

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23 Apr 2008, 00:02
I think it should be 40/100 (inso/total) , so prob . is 2/5 ?
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23 Apr 2008, 00:10
2) A has 4 prime factors. B has 3 prime factors. 15 is a common factor to A and B . How many prime factors does AB have.

Answer to this is 5 ? 2 common factors + 2 ( remaining prime factor for A) +1 (remaining prime factor for B)

3) An ellipse is inscribed in a rectangle . The area of an ellipse is given by 1/2 * pi* a * b , where a is the length of the minor axis , and b the major axis. What is the area of the ellipse .

I would go with E , since it is not given whether sides of rectangles are tangent to ellipse or not . What is OA?
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23 Apr 2008, 08:39
rpmodi wrote:
I think it should be 40/100 (inso/total) , so prob . is 2/5 ?

I think my answer is correct on this one.

Here is similar example. If you have even number after rolling dice, what is probability it is 2.

Answer here is 1/3 not 1/6

Let me know if you think I am not reading question correctly.
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23 Apr 2008, 08:43
Ans 2 - 5 (A has factors 3,5,x,y, B has factors 3,5,z so AB has 3,5,x,y,z)
Ans 3 - Not sure...but could be C. Inscribed means it is touching all sides of rectangle.

Anyone else on this Q 3.
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23 Apr 2008, 13:01
Yes you are right , inscribed means its tangent , I might be dreaming while woring on this one !
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23 Apr 2008, 19:39
bhatiagp wrote:
1)60% people have diabetes, and 56% have insomnia. None have neither. What is the probabaility that a person with insomnia has no diabetes.

2) A has 4 prime factors. B has 3 prime factors. 15 is a common factor to A and B . How many prime factors does AB have.

3) An ellipse is inscribed in a rectangle . The area of an ellipse is given by 1/2 * pi* a * b , where a is the length of the minor axis , and b the major axis. What is the area of the ellipse .

1) Length of the rectangle is 12

2) Breadth of the rectangle is 24.

1) Set x = both diabetes and insomnia
60-x + x + 56-x = 100
x= 16
Therefore, ONLY insomnia is: 56 - 16 = 40
P(only insomnia) = 40/100 = 2/5

2) I don't quite get the question, AB can have 5 primes or 4 primes
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23 Apr 2008, 22:04
1 ) 2/5

2) 5 factors

3) Need your opinion. Similiar question appeared for a friend, and Im not sure whether inscribed means rectangle sides are tangential to ellipse

Last edited by bhatiagp on 01 Jul 2008, 21:59, edited 1 time in total.
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23 Apr 2008, 22:13
bhatiagp wrote:
1 ) This is a question of conditional probability .

Probability that a person has insomina but no diabetes = 1 - ( Prob of Insomina and diabetes)
= 1- ( 16/56 ) = ( 40/56) = 5/7

you are finding a prob that a person has insomina but no diabetes. so take a person (with insomina but no diabetes) out of total.

so it should be 40/100 = 2/5 not 5/7.
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25 Apr 2008, 13:40
bhatiagp wrote:
1 ) This is a question of conditional probability .

Probability that a person has insomina but no diabetes = 1 - ( Prob of Insomina and diabetes)
= 1- ( 16/56 ) = ( 40/56) = 5/7

2) 5 factors

3) Need your opinion. Similiar question appeared for a friend, and Im not sure whether inscribed means rectangle sides are tangential to ellipse

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25 Apr 2008, 14:35
Q2 it is 5 factors
Is the answer for Q3 is 144*pi
Re: Math Questions   [#permalink] 25 Apr 2008, 14:35
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