Find the probability.

Question

A survey claims that 73% of Australia households have at least one credit card. Find the probability that in a random sample of 550 Australia households, 375 to 385 have at least one credit card.

Answer 1

You need p ( 375 < = X < = 385) where X is binomially distributed with p = 0.73, trials = 550

You can find p (X < = 385) on a TI 84 and then subtract p ( X <= 374)

to find p ( X < =385)

2nd vars

binomcdf

trials = 550

p = 0.73

x value = 385

giving 0.0633

work out p (X <= 374) in the same way

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you can also approximate the binomial with a normal distribution and find the probability that way