Inventory questions

Dear OTA,

Please explain with steps

Thanks

52. The following lots of a particular commodity were available for sale during the year:
Beginning inventory 10 units at $61
First purchase 25 units at $63
Second purchase 30 units at $64
Third purchase 15 units at $73

The firm uses the periodic system and there are 20 units of the commodity on hand at the end of the year. What is the amount of the inventory at the end of the year according to the average cost method? (Points: 4)
$1,300
$1,305
$1,415
$1,236

53. If the cost of an item of inventory is $60 and the current replacement cost is $65, the amount included in inventory according to the lower of cost or market is ________. (Points: 4)
$5
$60
$65
$125

54. During the taking of its physical inventory on December 31, 2008, Albert's Bike Shop incorrectly counted its inventory as $210,000 instead of the correct amount of $180,000. The effect on the balance sheet and income statement would be as follows: _________. (Points: 4)
assets overstated by $30,000;retained earnings understated by $30,000; net income statement understated by $30,000
assets overstated by $30,000;retained earnings understated by $30,000; no effect on the income statement
assets and retained earnings overstated by $30,000; net income overstated by $30,000
assets and retained earnings overstated by $30,000; net income understated by $30,000

55. If, while taking a physical inventory, the company counts their inventory figures more than the actual amount. How will the error affect their bottom line? (Points: 4)
No change to net income
Net income will be overstated
Net income will be understated
Only gross profit will be affected