If price exceeds average total cost, then economic profits exist and new firms or stores will be opened.

The confidence interval is p' - E p p' + E.
Let x count the number of days with thunderstorms,
p' is x/n = 28/92 = 0.304. The computation of E is shown at the top right. So, E = 0.079 and the confidence interval is 22.5% p 38.5%.

For a 99% confidence interval we find z(0.005), the cut-off for the top 0.5% of the normal distribution. Looking up 0.995 in the middle of the table the reading to the row/column values, we get
2 .575. Working with the formula for E we get E = 1.29. So, the 99% confidence interval is $72 - 1.29 m
$ 72 + 1.29 or $70.71 m $73.29.

None of the accounting depreciation methods represent the actual physical depreciation of the underlying asset. They are all assumptions made for convenient allocation of an asset's purchase price over the economic life of the asset. Besides, the accelerated depreciation method generates greater present value of tax savings over the straight line method.

Consumers will buy more due to the price drop.