A number is chosen at random from 10 to 30 both inclusive. What is the probability that the number is divisible by 3?

A.
(frac{2}{15}) 
B.
(frac{1}{10}) 
C.
(frac{1}{3}) 
D.
(frac{2}{5})
Correct Answer: Option C
Explanation
Sample space S = {10, 11, 12, … 30}
Let E denote the event of choosing a number divisible by 3
Then E = {12, 15, 18, 21, 24, 27, 30} and n(E) = 7
Prob (E) = (frac{n(E)}{n(S)})
Prob (E) = (frac{7}{21})
Prob (E) = (frac{1}{3})
There is an explanation video available below.