Aptitude - Problems on Numbers - Discussion

10. 

Find a positive number which when increased by 17 is equal to 60 times the reciprocal of the number.

[A]. 3
[B]. 10
[C]. 17
[D]. 20

Answer: Option A

Explanation:

Let the number be x.

Then, x + 17 = 60
x

x2 + 17x - 60 = 0

(x + 20)(x - 3) = 0

x = 3.


Sirisha said: (Feb 27, 2011)  
You substitute the options in the place of x. Then we get LHS=RHS.

Revathy said: (Oct 3, 2011)  
(x+20)(x-3)=0 is correct
hw did you arrive on x = 3?

Please explain the solving of equation.

Professor Tajinder said: (Nov 6, 2011)  
@Revathy

See we have (x-3)(x+20)=0

Now x-3=0
x=3

x+20=0
x=-20

But we have to find the postive no, so the answer is 3.

Hope you will undertand it.

Ravi said: (Mar 9, 2013)  
How we got (x-3)(x+20)?

Rajeev said: (Jun 21, 2013)  
@Ravi we have to subdivide the equation.

We have x2 + 17x - 60 = 0,

Now, x2+20x-3x-60 = 0 (we can write 17x as (20x-3x)).

x(x+20)-3(x+20).

Then (x-3)(x+20) = 0.

Rakesh said: (Nov 28, 2013)  
Find a positive number which when increased by 17 is equal to 60 times the reciprocal of the number.

But here you're not taking reciprocal of number to solve your just taking x.

Joe said: (Jan 23, 2014)  
Let the number be x but since we have 3,17,10 and 20 as the numbers but we don't know which is the correct one the here is the Equation,

x+17 = 60/x.
So am using 3 as my first number.

3(3+17) = 60/3*3.
3(20) = 20*3.

60 = 60.

Hence the Answer is 3.

Pankaj said: (Mar 25, 2014)  
I'm not understand reciprocal means in this question?

Sindhu said: (Aug 13, 2014)  
Reciprocal means if you take x reciprocal of x is 1/x.

Hariteja said: (May 26, 2015)  
Check from the options. It will be easy.

Naresh said: (Feb 13, 2016)  
Please tell about the detail of question.

Kausik said: (Feb 16, 2016)  
How you come to the assumption of x2+20x-3x-60 = 0 (we can write 17x as (20x-3x))?

20-3 = 17 is one of the assumptions for the result of 17, but how this can be narrowed to the right assumption?

Kabali said: (Jul 14, 2016)  
x2 + 12x + 5x - 60 = 0 also solution.
x(x + 12) - 5(x + 12) = 0.
Hence x = 5 is also the answer.

Denzel said: (Aug 9, 2016)  
How did you get x2 + 17x - 60 ?

Steven Than said: (Sep 25, 2016)  
Yes, I agree @Kabali.

The answer is 5.

Balag said: (Sep 29, 2016)  
5 is wrong. Because 12 * 5 = 60. Not -60. So it is wrong.

Debrupa said: (Aug 13, 2018)  
Reciprocal of x = 1/x.

Here, the equation should be ->
x+17=60*(1/x)
=> x=3,-20.

But, as we have to calculate +ve no only, so answer will be 3.

Raam said: (Mar 5, 2019)  
What if the number of times is 59 rather than 60? Please tell me.

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