Annual demand for a special soldering material is 3000 lbs. The holding cost is 24% per year, based on the purchase price. Order cost is $42 per order. The price schedule is as follows:

< 100 lbs.	$22 per pound
100 lbs. to 1000 lbs.	$21 per pound
More than 1000 lbs.	$20 per pound

Determine how much should be bought at a time.