Latest Elitmus Aptitude Question SOLUTION: if r>x>0 and r+x=121, then what is the probability that 1/(1/r + 1/x) is a whole number . given that r and x both are whole number... a) 1/10 b. 1/12 c. 1/11 d.) dont remember

• Placement Papers
• /
• Elitmus
• /
• Numerical Ability

Elitmus Question Papers:

(#M40151308) ELITMUS Numerical Ability question Keep an EYE

if r>x>0 and r+x=121, then what is the probability that 1/(1/r + 1/x) is a whole number . given that r and x both are whole number...

a) 1/10 b. 1/12 c. 1/11 d.) dont remember

Asked In Elitmus Nikhil Gupta (9 years ago)

Unsolved Read Solution (6)

Is this Puzzle helpful?   (8)   (2) Submit Your Solution

Read Solution (6) :

Sambuddha Chaudhuri  (9 years ago)

1/12 is the answer...
there would be 5 cases where it will give whole number....
(66,55)...(77,44)..,(88,33)...(99,22)...(110,11)....
out of the total no. of 60 case starting from (61,60) to (120,1)
so 5/60 =1/12 the ans

Is this solution Helpfull? Yes (9) | No   

deepak  (9 years ago)

have u got right answer ?
i think there is zero probability there is no any such chances that if x is less than r and 1/(1/r+1/x) is be whole number .

Is this solution Helpfull? Yes (1) | No   

Nikhil Gupta  (9 years ago)

i guess 1/12 is the correct answer .

r+x=121 with r>x>0
possible soln for this :
r=120 x=1
r=119, x=2
......
....
....
r=61, x=60 i.e. 60 soln bcoz for r=60 x=61 r

Is this solution Helpfull? Yes (1) | No   

Devendra Marghade  (9 years ago)

1/60

As 1/(1/r + 1/x)=r*x/(r+x) to be whole number r*x must be a multiple of (r+x)=121
Checking the values for r*x= 121*n for n=1,2,.... we have 121, 242, 363, 484, 605, 726, 847, 968, 1089, 1210,....
On observing these values 121=11*11, 242=11*22, 363=11*33,......,
For one value to be 11 other must be 110 that satisfies condition , so r*x=1210=11*110 and
For r+x=121, possible combinations of (r, x)=(1,120), (2,119), (3,118), ...........,(120,1), total 120
Out of which (r,x)=(11, 110) and (110,11) i.e. 2 cases are favorable.
So probability= 2/120=1/60

Is this solution Helpfull? Yes (1) | No (5)  

deepak  (9 years ago)

@Devendra M ur approach is right but x must be less than r..
@nikhil Gupta how is five possiblities ther??

Is this solution Helpfull? Yes (1) | No   

shruti jain  (9 years ago)

i didnt get ur solution plz elaborate...

Is this solution Helpfull? Yes | No   

Please Login to Read Solution.