Elitmus
Exam
Numerical Ability
Number System
Sum of 2 no is 50 and sum of their reciprocal is 1/12. So find these number? [
Read Solution (Total 9)
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- let numbers are x & (50-x)
then 1/x + 1/(50-x) = 1/12
=> x(50-x) = 600
=> (x-20)*(x-30) = 0
=> x = 20,30
numbers are 20,30 - 10 years agoHelpfull: Yes(42) No(0)
- let the nos be x and y, then x+y=50
and 1/x+1/y= 1/12
=> (x+y)/xy= 1/12
=> 50/xy=1/12
=> xy=60 => x(50-x)=60
=> (x-30)(x-20)=0
=> x= 20,30
hence the nos are 20,30
by d way i doubt that this was a question from Elitmus... its not an elitmus level question.
- 10 years agoHelpfull: Yes(10) No(0)
- first consider two nos. i.e. 'a' and 'b'
A/q
a+b=50 --------(1)
also
(1/a) + (1/b) = 1/12
on solving we get
(a+b)/ab=1/12
on putting the value from (1) we get
ab=600
Now solving through the substitution method will definitely give you the answer but I would say to hold this approach ,because its time consuming method , and use only when your hit and trial method does not work .
So
simply recapitulate the values whatever you have
a+b = 50
a*b = 600
so its clearly visible that the values must be 20,30 or vice versa . - 10 years agoHelpfull: Yes(3) No(0)
- their roots are 20 and 30
let the numbers be a,b
a+b=50
1/a + 1/b = 1/12
a+b/ab=1/12
50/ab=1/12
ab=600
a(50-a)=600
a2-50a+600=0
a=20,30 - 10 years agoHelpfull: Yes(1) No(0)
- 20 and 30 put in the both equation ans is yours
- 10 years agoHelpfull: Yes(0) No(0)
- 1/12 is the sum of reciprocal .
Make the denominator a multiple of 50.
1*50/12*50 = 50/600
Now 600 = 30 *20 which satifies both the criteria .
So ans is 30,20.
- 10 years agoHelpfull: Yes(0) No(0)
- let two numbers be x and 50-x
then a/c
1/x+1/(50-x)=1/12
hence solving this equ we get x=30 and 20
- 10 years agoHelpfull: Yes(0) No(0)
- 20+30=50
1/20*1/30=1/12 - 8 years agoHelpfull: Yes(0) No(0)
- option 1 -may i
- 8 years agoHelpfull: Yes(0) No(0)
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