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. 22)
22.
Three numbers which are co-prime to each other are such that the product of the first two is 551 and that of the last two is 1073. The sum of the three numbers is:
75
81
85
89
Answer: Option
Explanation:

Since the numbers are co-prime, they contain only 1 as the common factor.

Also, the given two products have the middle number in common.

So, middle number = H.C.F. of 551 and 1073 = 29;

First number = 551 = 19;    Third number = 1073 = 37.
29 29

Required sum = (19 + 29 + 37) = 85.

Discussion:
53 comments Page 4 of 6.

Diksha said:   9 years ago
Why the 29 divided the term. It's middle term but what logic behind this?

Ajit said:   8 years ago
Let me explain (551-1071) = 522 then again least no minus (551-522) = 29.

Divyanshu Priyadarshi said:   8 years ago
Let the three numbers be x, y and z.

Hence, xy=551 and yz=1073.
Middle number =HCF of 551 and 1073 = 29.
First number =551/29= 19.
Third number =1073/29= 37.
Required numbers are 19,29 and 37.

Surya Deep said:   8 years ago
Consider numbers as X, Y, Z respectively.

Now,

Consider product XY = 551 ------eq1
Consider product YZ = 1073 -----eq2

So, clearly common highest factor btw XY and YZ should be Y
i.e HCF (551,1073) = 29.

From eq 1, X=19.
from eq 2, Z=37.

Now, Add this numbers (X+Y+Z)
(19+29+37)=85 And.

Asaduzzaman said:   8 years ago
Thanks.

Muhammad safeer ahmed said:   7 years ago
a*b=551
b*c=1073

So, b is =1073-551=522,
522-551=29,
29 is middle and common term exist in both and b =29.

Put the value
a*b=551
a*29=551
a=551/29=19
a=19.

Put the value
b*c=1073
29*c=1073
C=1073/29=37.

So
a=19
b=29
c=37
19+29+37=85.
(6)

Anamika said:   7 years ago
Thanks all for the answer.
(1)

Dinu said:   7 years ago
@Jyoti.

30-1 = 29.
So,
80+5=85.

Abhoi said:   7 years ago
Thanks @Asutosh.

Tanu said:   7 years ago
Why we take HCF why not LCM? Please explain me.


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