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

n = 61 costumers

Explanation:

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

`n = (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 = ((2.33^(2))(0.5)(1-0.5))/(0.15^(2) )`

n = 60.32 costumers

n ≈ 61 costumers