In: Math
In a survey conducted to determine, among other things, the cost of vacations, 64 individuals were randomly sampled. Each person was asked to compute the cost of her or his most recent vacation. The sample showed a sample mean of $1810. Assuming that the population standard deviation σ is $600, construct a 90% confidence interval for the average cost of all vacations. (Round your final answer to 3 decimal places).
Solution :
Given that,
Point estimate = sample mean =
= $ 1810
Population standard deviation =
= $ 600
Sample size = n = 64
At 90% confidence level
= 1 - 90%
= 1 - 0.90 =0.10
/2
= 0.05
Z/2
= Z0.05 = 1.645
Margin of error = E = Z/2
* (
/n)
= 1.645 * ( 600 / 64
)
= 123.375
At 90% confidence interval estimate of the population mean is,
- E <
<
+ E
1810 - 123.375 <
< 1810 + 123.375
$ 1686.625 <
< $ 1933.375