Q. A three digit number, which is a multiple of 11, is chosen at random. Probability that the number so chosen is also a multiple of 9, is equal to
A) $\frac{1}{9}$
B) $\frac{2}{9}$
C) $\frac{1}{100}$
D) $\frac{9}{100}$
Explanation
(a)
Three digit numbers multiple of 11 are 110, 121,…,990 (81 numbers). Now number also divisible by 9 are divisible by 99. So, numbers are 198, 297,…,990(9 numbers).
So, required probability $= \frac{9}{81} = \frac{1}{9}$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.