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. 7)
7.
Three number are in the ratio of 3 : 4 : 5 and their L.C.M. is 2400. Their H.C.F. is:
40
80
120
200
Answer: Option
Explanation:

Let the numbers be 3x, 4x and 5x.

Then, their L.C.M. = 60x.

So, 60x = 2400 or x = 40.

The numbers are (3 x 40), (4 x 40) and (5 x 40).

Hence, required H.C.F. = 40.

Discussion:
41 comments Page 2 of 5.

Akash kandwal said:   7 years ago
Actually, the numbers given are in a ratio so we have to take in : 1/60.

So lcm:=1/2400,
and then,
The product of number=lcm of number*hcf of number;
1/60=1/2400*HCF.
HCF=40.

Mayur said:   3 years ago
Let's remember the common formula to find HCF or LCM whenever "ratio" is given,

LCM= LCM of ratio x HCF.
2400(given) = 60 x HCF,
HCF = 40.
(26)

Anurag said:   1 decade ago
@shrimant....

The formula works only for two number..for eg take num
2,4,8....hcf is 2

lcm is 16.

product of hcf and lcm=32

product of num=64.

Karthick said:   10 years ago
First we have to find original nos.

L.C.M = 2400.

Ratio = 3:4:5.

2400/3 = 800.
2400/4 = 600.
2400/5 = 480.

L.C.M of 800, 600, 480 = 40.

Aman Kaushik said:   1 decade ago
Ratio 3:4:5
LCM 2400.
HCF ?

Solve answer = 3*4*5 = 60.

LCM is = 2400.
HCF IS = 2400/60.
= 40.

Sunil sharma said:   1 decade ago
3*40 = 120.
4*40 = 160.
5*40 = 200.
So number is 120, 160, 200.

We are calculate LCM above three number = 2400.
Do answer is 40.

Aadi said:   9 years ago
I didn't understand one thing.

Why you guys convert ratio to multiplication?

For eg: 3 : 4 : 5 to 3 * 4 * 5 = 60.
2400/60 = 40?

Mehar said:   1 decade ago
Simple way to ans:

three numbers L.C.M=2400;
3x*4x*5x=2400 ==> x(60)=2400;
==> x=40;

Therefore ==> H.C.F=40;

Khagendra Thapa Kazzi said:   2 months ago
Let the numbers be 3x, 4x and 5x.
Then, their L.C.M. = 60x.
So, 60x = 2400 or x = 40.
Hence, the required H.C.F. = 40.
(2)

Ramya said:   8 years ago
What is the relationship between the product of three numbers and their L.C.M and H.C.F. Please, anyone explain me?


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