Question

The manager of a supermarket wants to obtain information about the proportion of customers who dislike a new policy on cashing checks. How many customers should he sample if he wants the sample fraction to be within .15 of the true fraction, with probability .98

Answer 1

Answer:

n = 61 costumers

Step-by-step explanation:

For calculating the number of costumers he should sample we use the next equation:

$n = \frac{z_{1-\alpha/2}^{2}p(1-p)}{E^{2} }$

                          Where E is the error that we are prepared to accept, in this  case E = 0.15

How we don't know the value of p, we can estimate it like p = 0.5

∝ = 1-0.98 = 0.02

1-∝/2 = 0.99

$z_{0.99} = 2.33$

$n = \frac{(2.33^{2})(0.5)(1-0.5)}{0.15^{2} }$

n = 60.32 costumers

n ≈ 61 costumers