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Maths, Addmaths and Statistics: Post your doubts here!

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RoaringInferno

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People! I need help in a Statistics Question :/
November 1993, P2, Q3.
It's something about which events are mutually exclusive and which ones are independent. I know the answers are
(i) Events A and B are mutually exclusive.
(ii) Events C and D are independent.
(iii) A,B and C are not mutually exclusive since their sum exceeds 1.
But can anybody EXPLAIN as to how I can arrive at these conclusions?
Any help would be appreciated. Thanks.
 
Haris Bin Zahid

Haris Bin Zahid

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RoaringInferno said:
People! I need help in a Statistics Question :/
November 1993, P2, Q3.
It's something about which events are mutually exclusive and which ones are independent. I know the answers are
(i) Events A and B are mutually exclusive.
(ii) Events C and D are independent.
(iii) A,B and C are not mutually exclusive since their sum exceeds 1.
But can anybody EXPLAIN as to how I can arrive at these conclusions?
Any help would be appreciated. Thanks.
Click to expand...
What's the question?????? If u have a 20 yrs older paper doesn't mean that everyone has it.:p:p:p
 
R

RoaringInferno

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I assumed they would -.- My bad.
P(A) + P(B) = p(A or B)
P(A) + P(B) +P(C) = 1.5
P(C and D)= P(C) x P(D)
(1) Write down any two mutually exclusive events from A, B, C and D.
(2) Write down any two independent events from A, B, C and D.
(3) What can you tell about the events A, B and C?
Yeah I think that's it.
 
Haris Bin Zahid

Haris Bin Zahid

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RoaringInferno said:
I assumed they would -.- My bad.
P(A) + P(B) = p(A or B)
P(A) + P(B) +P(C) = 1.5
P(C and D)= P(C) x P(D)
(1) Write down any two mutually exclusive events from A, B, C and D.
(2) Write down any two independent events from A, B, C and D.
(3) What can you tell about the events A, B and C?
Yeah I think that's it.
Click to expand...
(1) First let me tell you about the properties of Mutually exclusive events:
These are events in which one outcome does not effect the other. e.g. assume that there are 10 balls in a bag, 3 red and 7 blue. You draw out a ball and replace it again. The number of balls of each colour is unchanged and the probability remains the same each time u draw out a ball.
P (red) =3/10 and P (blue)=7/10.
The Probability (red or blue) is obviously 1, as of course you'll draw out a ball out of these.
So, P(red) +P(blue)=P(red or blue)-----> 3/10 + 7/10 = 1, which means that the events are mutually exclusive. The total probability of mutually exclusive events is always 1. So it is a property of mutually exclusive events that P(A) + P(B)=P(A or B). Thus, A and B are mutually exclusive.

(3) The total probability of A, B and C is not 1. Thus, they are not mutually exclusive.

(2) For independent events, I think it's in Dean Thomas' book that P(A) x P(B)=P(A and B). Check it out as I don't remember much about it bcz I gave Stats paper last year and I don't even have the book now. But do note that events which are mutually exclusive can never be independent.
 
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RoaringInferno

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Haris Bin Zahid said:
(1) First let me tell you about the properties of Mutually exclusive events:
These are events in which one outcome does not effect the other. e.g. assume that there are 10 balls in a bag, 3 red and 7 blue. You draw out a ball and replace it again. The number of balls of each colour is unchanged and the probability remains the same each time u draw out a ball.
P (red) =3/10 and P (blue)=7/10.
The Probability (red or blue) is obviously 1, as of course you'll draw out a ball out of these.
So, P(red) +P(blue)=P(red or blue)-----> 3/10 + 7/10 = 1, which means that the events are mutually exclusive. The total probability of mutually exclusive events is always 1. So it is a property of mutually exclusive events that P(A) + P(B)=P(A or B). Thus, A and B are mutually exclusive.

(3) The total probability of A, B and C is not 1. Thus, they are not mutually exclusive.

(2) For independent events, I think it's in Dean Thomas' book that P(A) x P(B)=P(A and B). Check it out as I don't remember much about it bcz I gave Stats paper last year and I don't even have the book now. But do note that events which are mutually exclusive can never be independent.
Click to expand...
For (!) and (2), my solutions were the same as yours with the same chain of thought. For (3) I reasoned that P(A) x P(B) = 0 for all Mutually Exclusive events and P(C) x P(D) =P(A and D) isn't equal to zero, so it must be independent :p Ironically I solved it like 5 minutes after I posted the question. Still, thanks for taking the time to reply :)
 
stranger mujtaba

stranger mujtaba

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express the ratio 24 cm to 3 m in its lowest terms. Give your answer in the form p:q, where p and q are integers.

plz help me i cant solve this question...plzplz
 
T

Tharindu

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stranger mujtaba said:
express the ratio 24 cm to 3 cm in its lowest terms. Give your answer in the form p:q, where p and q are integers.

plz help me i cant solve this question...plzplz
Click to expand...
Lol...heres how you do it
24:3
Now divide both sides by 3, you get-
8:1
This is the answer....
 
stranger mujtaba

stranger mujtaba

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express the ratio 700 g to 1.75 kg in its lowest terms.
Give your answer in the form m:n, where m and n are integers
 
stranger mujtaba

stranger mujtaba

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the mass of container and its contents is 2.4 kg. the mass of the content is 750 g.
calculate the mass in kilograms, of the container
 
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