A square tile has side 30cm. How many of these tiles will cover a rectangular floor of length 7.2m and width 4.2m?

A.
336 
B.
420 
C.
576 
D.
720
Correct Answer: Option A
Explanation
Total floor area = 720 x 420
Area of one tile = 30 x 30
No. of tile required = (frac{720 times 420}{30 times 30})
= 24 x 14
= 336 tiles