Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 26)
26.
The difference between a positive proper fraction and its reciprocal is 9/20. The fraction is:
Answer: Option
Explanation:
| Let the required fraction be x. Then | 1 | - x = | 9 |
| x | 20 |
 |
1 - x2 | = | 9 |
| x | 20 |
20 - 20x2 = 9x
20x2 + 9x - 20 = 0
20x2 + 25x - 16x - 20 = 0
5x(4x + 5) - 4(4x + 5) = 0
(4x + 5)(5x - 4) = 0
| x = | 4 |
| 5 |
Discussion:
53 comments Page 3 of 6.
Pooja said:
8 years ago
@ Rima.
The numerator is less than the denominator.
Examples: 1/3, 3/4, 2/7. Improper Fractions: The numerator is greater than (or equal to) the denominator.
The numerator is less than the denominator.
Examples: 1/3, 3/4, 2/7. Improper Fractions: The numerator is greater than (or equal to) the denominator.
Janu said:
1 decade ago
If we assume that the +ve fraction would be x
then x + (9/20) = 1/x (ex: x+y=z => y=z-x)
So (1/x) - x = (9/20)...
Hope you understand...
then x + (9/20) = 1/x (ex: x+y=z => y=z-x)
So (1/x) - x = (9/20)...
Hope you understand...
Prithviraj chauhan said:
9 years ago
You can take it as, a/b - b/a = 9/20.
a2 - b2 /ab =9/20 then equate ab = 20 options are 1 * 20, 2 * 10, 4 * 5 and here we get our answer guys.
a2 - b2 /ab =9/20 then equate ab = 20 options are 1 * 20, 2 * 10, 4 * 5 and here we get our answer guys.
Akshat said:
8 years ago
The conventional approach will be the lengthy one for this question.
So by checking all the options we get the option (d),
i.e 5/4-4/5 = 9/20.
So by checking all the options we get the option (d),
i.e 5/4-4/5 = 9/20.
Kazibwe Moses said:
3 years ago
4/5 is wrong it will give us a negative answer.
If we are to prove it;
4/5-its reciprocal,
4/5-5/4 = ((16/25)/20) = -9/20.
If we are to prove it;
4/5-its reciprocal,
4/5-5/4 = ((16/25)/20) = -9/20.
(15)
Anil said:
1 decade ago
@janu:
If we assume +proper fraction to be x then x-(9/20)=(1/x), and not as you said...
I think this is wrong..
If we assume +proper fraction to be x then x-(9/20)=(1/x), and not as you said...
I think this is wrong..
Samyuktha said:
8 years ago
If the ans is 4/5.
4/5 - 5/4 should be 9/20 which is not right.. 4/5 - 5/4 is - 9/20.
The answer should be 5/4.
4/5 - 5/4 should be 9/20 which is not right.. 4/5 - 5/4 is - 9/20.
The answer should be 5/4.
Shama M said:
4 years ago
Since they have mentioned proper fraction (which is always less than 1), we assumed the difference to be 1/x - x.
(2)
Prateek said:
1 decade ago
As the ans is 9/20, it means lcm of numerator & denomenator should be 20. 4/5 only satisfies the above cond.
Shiva said:
8 years ago
Positive proper function is in form of 1/x and its reciprocal is x that why we are considering 1/x - x = 9/20.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers