SOLUTION: A recent survey found that 50% of mobile phone users, between the ages of 18 to 34, had a smartphone. Suppose a random sample of 20 mobile phone users were selected. What is the pr

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Question 913261: A recent survey found that 50% of mobile phone users, between the ages of 18 to 34, had a smartphone. Suppose a random sample of 20 mobile phone users were selected. What is the probability that less than 5 of them have a smartphone? [Ensure that you (a) clearly denote the probability distribution and its parameter(s) and its parameter(s) and (b) state the formula].

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Binomial Distribution: p(have) = .50, n = 20
P(x < 5) = binomcdf(20, .50, 4) Using TI
...........
Computed Individually and sum determined.
Using P+%28x%29=+highlight_green%28nCx%29%28p%5Ex%29%28q%29%5E%28n-x%29+
p and q are the probabilities of success and failure respectively.
In this case p = .50 and q = .50, n = 20
nCx+=+%28n%21%29%2Fx%21%28n+-+x%29%21%29
P(x < 5) = P(0) + P(1) + P(2) + P(3) + P(4)