Statistics And Probability Question 258
Question: Five digit numbers are formed using the digits 1, 2, 3, 4, 5, 6 and 8. What is the probability that they have even digits at both the ends
[RPET 1999]
Options:
A) $ \frac{2}{7} $
B) $ \frac{3}{7} $
C) $ \frac{4}{7} $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
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By using digits 1, 2, 3, 4, 5, 6 and 8, total 5 digits numbers = $ ^{7}P_5 $ And number of ways to form the numbers, they have even digit at both ends $ =4\times 3{{\times }^{5}}P_3 $
$ \therefore $ Probability $ =\frac{4\times 3{{\times }^{5}}P_3}{^{7}P_5}=\frac{2}{7} $ .
BETA
