Quantitative Aptitude Ques 2250
Question: If a 4 digit number is formed at random using the digits 1, 3, 5, 7 and 9 without repetition, thus the probability that it is divisible by 5 is
Options:
A) $ \frac{4}{5} $
B) $ \frac{3}{2} $
C) $ \frac{1}{5} $
D) $ \frac{2}{3} $
Show Answer
Answer:
Correct Answer: C
Solution:
- Number of four-digit numbers which are formed with $ 1, $ $ 3, $ $ 5, $ $ 7, $ $ 9={}^{5}P _4 $ $ =5\times 4\times 3\times 2=120=n(s) $ The number which are divisible by $ 5={}^{4}P _3 $ $ =4\times 3\times 2=24=n(E) $
$ \therefore $ $ P(E)=\frac{n(E)}{n(S)}=\frac{24}{120}=\frac{1}{5} $
BETA
