Number System
Aptitude

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Q.

The LCM of two numbers is 280 and their ratio is $7:8$. The two numbers are

 A.

70, 80

 B.

35, 40

 C.

42, 48

 D.

28,32

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Solution:
Option(B) is correct

Let the number be $7x$ and $8x$
HCF $= x$

Hence, $\text{HCF × LCM} = 7x × 8x$
⇒ $280x = 56 x×x$
⇒ $x= 5$
Thus numbers are 35 and 40.


(2) Comment(s)


SAUROJIT
 ()

7*P=280 ..=>P=40

8*Q=280..=>Q=35



Gopal
 ()

l.cm of 280=l.cm of the a,b(choose all the option and workout)

take l.c.m for 280 = 7*8*5

take each option and l.c.m

70,80 2*5*7*8 answer is wrong

35, 40 7*8*5 answer is same as 280 l.cm

hope this is helpfull