Answer:
a) Sample Mean = 79.4
Sample standard deviation = 30.62
b) 90% Confidence interval: (67.56 ,91.24)
Step-by-step explanation:
We are given the following in the question:
Prices for sleeping bags has an approximately normal distribution.
We are given the following sample:
35, 85, 105, 40, 100, 50, 30, 23, 100, 110, 105, 95, 105, 60, 110, 120, 95, 90, 60, 70
a)
Formula:
where are data points, is the mean and n is the number of observations.
Sum of squares of differences = 1971.36 + 31.36 + 655.36 + 1552.36 + 424.36 + 864.36 + 2440.36 + 3180.96 + 424.36 + 936.36 + 655.36 + 243.36 + 655.36 + 376.36 + 936.36 + 1648.36 + 243.36 + 112.36 + 376.36 + 88.36 = 17816.8
b) 90% Confidence interval:
Putting the values, we get,