Answer:
649
Step-by-step explanation:
Given that
Mean number of dresses is 5.5
Standard deviation of the sample, S.D is 1.3
Margin of error, M.E is 0.1
Level of confidence is 95% or 0.95
The formula for margin of error, M.E is
Z * (S.D/√n) , where
Z = Value for level of confidence which is 1.96
Proceeding further, we have
0.1 = 1.96 * (1.3/√n)
0.1 = 2.548 / √n, making √n subject of formula, we have
√n = 2.548 / 0.1
√n = 25.48, squaring both sides
n = 25.48²
n = 649.23
Therefore the number of sample size we're looking for is n = 649.23, when rounded to the nearest integer, we have it to be 649
