According to J.D. Power & Associates, the mean purchase price of a smartphone device (such as an iPhone or Galaxy) in 2016 was $318. In 2017, a random sample of 20 business managers who owned a smartphone device showed a mean purchase price of $341 with a sample standard deviation of $23.

(a) At α = .05, has the mean purchase price increased? State the hypotheses and decision rule clearly.

(b) Use Excel to find the p-value and interpret it.