Question

Use the appropriate normal distribution to approximate the resulting binomial distributions. A convenience store owner claims that 55% of the people buying from her store, on a certain day of the week, buy coffee during their visit. A random sample of 35 customers is made. If the store owner's claim is correct, what is the probability that fewer than 22 customers in the sample buy coffee during their visit on that certain day of the week?

a) 0.7967

b) 0.7764

c) 0.8238

d) 0.7224

e) 0.8413

f) None of the above.

Answer 1

Use continuity correction, P(x<a) = 1-P(x<a-0.5)

Refer Standard normal table/Z-table to find the probability OR use excel formula "=NORM.S.DIST(0.76, TRUE)" to find the probability.