Aptitude - Problems on H.C.F and L.C.M - Discussion
Discussion Forum : Problems on H.C.F and L.C.M - General Questions (Q.No. 30)
30.
If the sum of two numbers is 55 and the H.C.F. and L.C.M. of these numbers are 5 and 120 respectively, then the sum of the reciprocals of the numbers is equal to:
Answer: Option
Explanation:
Let the numbers be a and b.
Then, a + b = 55 and ab = 5 x 120 = 600.
 The required sum = |
1 | + | 1 | = | a + b | = | 55 | = | 11 |
| a | b | ab | 600 | 120 |
Discussion:
37 comments Page 1 of 4.
Aakash Choudhary said:
5 years ago
Let the number be 5a and 5b.
Given HCF= 5 LCM =120.
Sum=55.
5a+5b=55.
=> a+b=11 ------> (1)
By property product of numbers= LCM*HCF.
5a*5b= 5*120
=> 5ab= 120 --------> (2).
Now sum of reciprocal of numbers:-
(1/5a) + (1/5b) = a+b/5ab.
Putting values from (1) and (2).
(1/5a) + (1/5b)= 11/120.
Given HCF= 5 LCM =120.
Sum=55.
5a+5b=55.
=> a+b=11 ------> (1)
By property product of numbers= LCM*HCF.
5a*5b= 5*120
=> 5ab= 120 --------> (2).
Now sum of reciprocal of numbers:-
(1/5a) + (1/5b) = a+b/5ab.
Putting values from (1) and (2).
(1/5a) + (1/5b)= 11/120.
(2)
Ankur said:
9 years ago
Guys! LCM * HFC = PRODUCT OF TWO NUMBERS. This is the rule.
(1)
Lucas said:
9 years ago
Please solve this question for me.
Two bulbs flash at regular intervals of 30 and 36 seconds respectively. They flash together at 10.45. At what time will they flash together?
(a) a second time.
(b) a 5th time.
Two bulbs flash at regular intervals of 30 and 36 seconds respectively. They flash together at 10.45. At what time will they flash together?
(a) a second time.
(b) a 5th time.
SURAJIT HALDER said:
9 years ago
If the sum of two numbers is 110 and LCM of those two numbers are 300. Find two numbers?
Can anyone answer this question?
Can anyone answer this question?
Sonu said:
9 years ago
How can we solve this? Let me know the method of solution.
Diviya priya said:
9 years ago
If the sum of the 2 numbers is 220 and the LCM is 99. Then find the HCF?
Anisa said:
9 years ago
If LCM of two number is 729, then HCF is? Please give me the solution.
Deshraj said:
9 years ago
How can we find out the co-prime of any numeric number? Explain.
M veeresh said:
9 years ago
@Anisa.
The Lcm of 2 numbers is 729. Find lcm to 729 it will be 81 then 81 * x = 729.
i.e. x = 81 then the other number is 9. i.e. 81, 9 HCF is 9.
The Lcm of 2 numbers is 729. Find lcm to 729 it will be 81 then 81 * x = 729.
i.e. x = 81 then the other number is 9. i.e. 81, 9 HCF is 9.
Nirmala said:
9 years ago
Find the sum 7/16 + 5/24.
Give me the answer with the proper explanation.
Give me the answer with the proper explanation.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers