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 24 customers in the sample buy coffee during their visit on that certain day of the week?

Answer 1

Answer:

0.9256

Step-by-step explanation:

Given that 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

Let X be the number of customers who buy from her store, on a certain day of the week, buy coffee during their visit

X is Binomial (35, 0.55)

since each customer is independent of the other and there are two outcomes.

By approximation to normal we find that both np and nq are >5.

So X can be approximated to normal with mean = np = 19.25

and std dev = $\sqrt{npq} \\=2.943$

Required probability = prob that fewer than 24 customers in the sample buy coffee during their visit on that certain day of the week

= $P(X$ (after effecting continuity correction)

= 0.9256