PQR Ltd. presents the following financial information:

• Cash and cash equivalents: $40,000
• Accounts receivable: $60,000
• Inventory: $30,000
• Total current liabilities: $70,000
• Total assets: $400,000
• Total liabilities: $150,000
• Net income: $40,000

Compute: a) Acid-test ratio b) Inventory turnover c) Return on total assets d) Profit margin ratio