The income statements for Graul Corporation for the 3 years ending in 2019 appear below.

During 2019, Graul discovered that the 2017 ending inventory had been misstated due to the following two transactions being recorded incorrectly.
a. A purchase return of inventory costing $42,000 was recorded twice.
b. A credit purchase of inventory made on December 20 for $28,500 was not recorded. The goods were shipped F.O.B. shipping point and were shipped on December 22, 2017.
Required:
1. Was ending inventory for 2017 overstated or understated? By how much?
2. Prepare correct income statements for all 3 years.
3. Did the error in 2017 affect cumulative net income for the 3-year period? Explain your response.
4. Why was the 2019 net income unaffected?