According to the last census 45 of working women held fullti

According to the last census, 45% of working women held full-time jobs in 2002. If a random sample of 10 working women is drawn:

PLEASE SHOW ME HOW

1) What is the probability that at least two working women held full-time jobs?

2) What is the standard devation of the number of working women that held fulltime jobs?

Solution

1.

Note that

P(at least 2) = 1 - P(at most 1)

Using a cumulative binomial distribution table or technology, matching          
          
n = number of trials =    10      
p = the probability of a success =    0.45      
x = the number of successes =    1      
          
Then the cumulative probability is          
          
P(x <=   1   ) =    0.023257101

Thus,

P(at least 2) = 0.976742899 [ANSWER]

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2.

Note that

s = sqrt[n p(1 - p)]

where n = sample size = 10
p = probability of success = 0.45

Thus,

s = 1.5732 [ANSWER]