Probability Question 16

Question: The records of a hospital show that 10% of the cases of a certain disease are fatal. If 6 patients are suffering from the disease, then the probability that only three will die is

[MP PET 1998]

Options:

A) $ 1458\times {10^{-5}} $

B) $ 1458\times {10^{-6}} $

C) $ 41\times {10^{-6}} $

D) $ 8748\times {10^{-5}} $

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Answer:

Correct Answer: A

Solution:

Probability of disease is fatal = $ p=10% $

$ p=\frac{10}{100}=\frac{1}{10},q=\frac{9}{10} $

Number of patients = 6,

Number of die cases = 3
$ \therefore $ Probability that 3 will die $ ={}^{6}C_3{{( \frac{1}{10} )}^{3}}{{( \frac{9}{10} )}^{3}}=1458\times {10^{-5}} $ .