If two of the foue expressions x+y,x+5y,x-y,5x-y are chosen at random,what is the probability taht their product will be of the form of x2-(by)2, where b is an interger?
a>1/2
b>1/3
c>1/4
d>1/5
e>1/6
OA is E
Probability
This topic has expert replies
-
- Master | Next Rank: 500 Posts
- Posts: 338
- Joined: Fri Apr 17, 2009 1:49 am
- Thanked: 9 times
- Followed by:3 members
-
- Master | Next Rank: 500 Posts
- Posts: 338
- Joined: Fri Apr 17, 2009 1:49 am
- Thanked: 9 times
- Followed by:3 members
two numbers satisty the condition x^2 - Y^2
selecting two things out of a total of 2 things (2 pairs )is 1 = 2c2
selecting two things out of a total of 2 things (2 pairs )is 1 = 2c2
Last edited by kaulnikhil on Sun Aug 23, 2009 9:03 am, edited 1 time in total.
I am just confused. Please help me understand.
I understood Total selection = 4C2 = 6
But, we have a choice between 2 pairs. We can select them in 2C1 ways.
1st pair: x+y and x-y Here b = 1
2nd pair: x+5y and x-5y. Here b = 5
So isn't the answer 2/6 = 1/3?
Am I doing something wrong/?
I understood Total selection = 4C2 = 6
But, we have a choice between 2 pairs. We can select them in 2C1 ways.
1st pair: x+y and x-y Here b = 1
2nd pair: x+5y and x-5y. Here b = 5
So isn't the answer 2/6 = 1/3?
Am I doing something wrong/?
-
- Master | Next Rank: 500 Posts
- Posts: 338
- Joined: Fri Apr 17, 2009 1:49 am
- Thanked: 9 times
- Followed by:3 members
read the question
2nd pair: x+5y and x-5y. Here b = 5
the two pairs u talking about are 5x-y and x+5y
2nd pair: x+5y and x-5y. Here b = 5
the two pairs u talking about are 5x-y and x+5y
-
- Master | Next Rank: 500 Posts
- Posts: 338
- Joined: Fri Apr 17, 2009 1:49 am
- Thanked: 9 times
- Followed by:3 members
x+y and x-y
are the only two pairs which give us a solution in the form mentioned in the question
we have 2 no and we have to select a pair from them ...this can be done in 2c2 ways = only one way ....
are the only two pairs which give us a solution in the form mentioned in the question
we have 2 no and we have to select a pair from them ...this can be done in 2c2 ways = only one way ....