SOLUTION: Question #9: Working Women and Computer Use It is reported that 72% of working women use computers at work. Choose 5 working women at random. Find a. The probability that at le

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Question 1194572: Question #9: Working Women and Computer Use
It is reported that 72% of working women use computers at work. Choose 5 working women at random. Find
a. The probability that at least 1 doesn’t use a computer at work

Found 2 solutions by math_tutor2020, ikleyn:
Answer by math_tutor2020(3817) About Me  (Show Source):
You can put this solution on YOUR website!

This is a binomial probability distribution problem.

n = 5 = sample size
p = 1-0.72 = 0.28 = probability of a woman not using a computer at work.

The binomial probability formula we'll use is this
P(x) = (n C x)*(p)^x*(1-p)^(n-x)
The n C x refers to the nCr combination formula.
x = number of women who do not use a computer at work

Plug in x = 0 to find the probability of exactly 0 women not using a computer at work
P(x) = (n C x)*(p)^x*(1-p)^(n-x)
P(0) = (5 C 0)*(0.28)^0*(1-0.28)^(5-0)
P(0) = (1)*(0.28)^0*(1-0.28)^(5-0)
P(0) = 0.1934917632

Then compute the complementary probability.
P(at least one does not use a computer) = 1 - P(zero women do not use a computer)
P(at least one does not use a computer) = 1 - P(0)
P(at least one does not use a computer) = 1 - 0.1934917632
P(at least one does not use a computer) = 0.8065082368
This works because we have two options: Either zero women do not use a computer at work, or at least one woman does not use a computer at work.

The longer method would be to compute it like this
P(X ≥ 1) = P(1) + P(2) + P(3) + P(4) + P(5)
I'll let you compute the individual values P(1) through P(5). Follow similar steps mentioned when I computed P(0).

Answer: 0.8065082368
Round this value however your teacher instructs.


Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.
Question #9: Working Women and Computer Use
It is reported that 72% of working women use computers at work.
Choose 5 working women at random. Find
a. The probability that at least 1 doesn’t use a computer at work
~~~~~~~~~~~~~~~~~~

The probability that one randomly selected working women uses a computer at work is 0.72,
according to the problem.


The probability that of 5 randomly selected working women all 5 use computers at work
is  0.72%5E5 = 0.193492 (rounded).


The probability that of 5 randomply selected working women at least one doesn't use a computer 
at work is the complement to it

    P = 1 - 0.72%5E5 = 1 - 0.193492 = 0.806508 = 80.6508%.    ANSWER

Solved.

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To see many other similar  (and different)  solved problems of this type,  look into the lessons
    - Solving probability problems using complementary probability
    - Solving probability problems using complementary probability REVISITED
in this site.

Learn the subject from there.