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 1 of 6.

Anjali said:   1 decade ago
I didn't understand this question. Please help me.

Aparna said:   1 decade ago
Nothing to worry,

see in HCF we get a number which is common to both numbers.

So find the hcf of 551 and 1073, we get 29

which is one number among three nos.

Let other two numbers be a and b

Given
a*29=551
a=551/29
a=19

Now,
b*29=1073
b=37

Hence three numbers. are 29,19,37
(16)

Vishnu said:   1 decade ago
Awesome way of explaining :-)

Uttam said:   1 decade 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, Y=37.

Pls comment if my assumption is wrong.

Vinayak said:   1 decade ago
@uttam. You are right.

Sangeeta said:   1 decade ago
How to know that 29 is the common factor?

Please tell me?

Prasant said:   1 decade ago
How to find 29 ? Is there any shortest way?

Ashutosh said:   1 decade ago
Hello friends its simple to get 29.

1 step:-1073-551 we will get 522.
Now,
2 step:- 551-522 we will get 29

Rahul said:   1 decade ago
Can any one tell me how to calculate HCF/LCM of big numbers in easy way?

Mustafa Ahmed said:   1 decade ago
How to find 29? Please show the divided process.


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