Question

Find the L.C.M. of $\frac{4}{5}$, $\frac{5}{6}$ and $\frac{7}{15}.$

• A. $140$
• B. $120$
• C. $70$
• D. $210$

Answer 1

The correct option is A $140$

Since, LCM of fraction = $\frac{\text{LCM of~numerators}}{\text{HCF of denominators}}$

$=\frac{\text{LCM of}4,5,7}{\text{HCF of}5,6,15}$

Since, the numbers $4,5,7$ has no common multipliers, so their product is $4\times 5\times 7=140$ is the LCM.
Similar way, the numbers $5,6,15$ has no common multipliers, so their HCF is $1$.

Therefore, LCM of given fractions $=\frac{140}{1}=140$