Math, asked by abiramisakthivel, 2 months ago

From the known data, there is roughly an 85% chance that a person of age 20 years will be
alive at age 75 years. Suppose that 4 people of age 20 years are selected at random. What
is the probability that the number alive at age 75 years will be at least 3?
0.1095
0.8905
0.3685
0.5520

Answers

Answered by amandeep9498
14

Step-by-step explanation:

ME know what I should have been looking forward with a block

Answered by ChitranjanMahajan
0

The answer is the third option, 0.8905

Given

  • 85% chance that a person of age 20 years will be alive at the age of 75 years
  • 4 people of age 20 years are selected at random.

To Find

the probability that the number alive at age 75 years will be at least 3

Solution

Let A be the event that a person at the age of 20 will live till the age of 75.

P(A) = 85%

= 85/100

= 17/20

Therefore P(not A) = 1 - P(A)

= 1 - 17/20

= 3/20

The probability that at least 3 people are alive till the age of 75 years out of 4 20 years people is

The probability that 3 out of 4 of them is alive + the Probability that all 4 of them are alive

The probability that 3 out of 4 of them are alive

= ⁴C₃ X P(A) X P(A) X P(A) X P(not A)

= 4!/3! X17/20 X 17/20 X 17/20 X 3/20

= 58956/160000

the Probability that all 4 of them are alive

= ⁴C₄ X P(A) X P(A) X P(A) X P(A)

= ⁴C₄ X 17/20 X 17/20 X 17/20 X 17/20

= 83,521/160000

Therefore,

The probability that at least 3 people are alive till the age of 75 years out of 4 20 years people  

= 58956/160000 + 83,521/160000

= 142477/160000

= 0.8905 (approx)

Hence, the answer is the third option, 0.8905

#SPJ2

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