Subject: General Aptitude · Chapter: Area · Exam: 2010 · Marks: · Difficulty:
A small ring of negligible thickness and radius 2 cm moves on a bigger rung of radius 10 cm. How many rotations will the small ring take on the bigger ring to make a complete round?
(a)5
(b)6
(c)7
(d)10
Answer
Answer (as printed): A
Explanation
Required number of rotations $$=\frac{\text { Circumference of bigger ring }}{\text { Circumference of smaller ring }}=\frac{2 \times \pi \times 10}{2 \times \pi \times 2}=5 .$$
Explanation as extracted from the printed page; notation may be imperfect.