Find the least length of a rod which can be cut into exactly equal strips, each of either 40cm or 48cm in length

A.
120cm 
B.
240cm 
C.
360cm 
D.
480cm
Correct Answer: Option B
Explanation
The least length is (frac{40}{48}) = (frac{5}{8})
for the rod to be cut in exactly equal trips
Ratio (frac{5}{6}) : (frac{48}{40})
(frac{frac{5}{6}}{frac{40}{48}}) = 1
(frac{5}{6}) x (frac{48}{40}) = (frac{240}{240}) = 1
The least length = 240cm