IIT JEE , AIEEE Forum - Mathematics , Algebra

navi

1.if a=i+j,b=j+k,c=k+i.....then

1.[a b c] =
2.[a+b b+c c+a] =
3.[a-b b-c c-a] =
4.[a+2b b+2c c+2a] =

2. 3 diff no;s r selected at random from the set A={1,2,3,.........10}...the probability that the product of 2 of the no;s is equal to the 3rd side is...............

3. if X is a poisson variate such that P(X=2)=9P(x=4)+90P(X=6)...THE mean of x is....

nitin62225

1)a ans=2,solve others like this only

2)ans =1/40

aysh

2)Let the largest of the 3 nos. be x.
Clearly, x cannot be prime
{becoz a prime no. has only 1 and the no. itself as its factors}
Now,
for x=1 and x=4, there are no cases such that all the three nos. are distinct.
For x=6, the other 2 nos. can be 2,3.
Thus, reqd. no. of cases=3!=6
For x=8, the other 2 nos. can be 2,4
Thus, reqd. no. of cases=3!=6
For x=9, there are no cases such that all the three nos. are distinct.
For x=10, the other 2 nos. can be 2,5
Thus, reqd. no. of cases=3!=6
No. of favourable cases=18
Total no. of cases=10P3
Thus, reqd. probability=18/(10P3)
=1/40.

PLEASE RATE IF CORRECT...

nitin62225

the set of favorable triplets are (2,6,3), (8,2,4), (2,5,10)

and u can select a triplet of 3 distinct digits out of 10 in 10C3 ways

fav selection is 3c1

there4 the probability is 3C1/10C3= 1/40

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