A supervisor needs to produce widgets. Two machines are able to make widgets. Machine A takes 2 hours to set up and can then make widgets at a rate of 80 per hour. The machine does not have to be stopped once it is running. Machine B takes 30 minutes to set up and can then make widgets at the rate of 60 per hour, but every 2 hours the machine has to be stopped and lubricated. Lubrication takes 30 minutes. All costs are calculated at a rate of $40 per hour. Draw a chart to compare costs. Read from the chart: The least cost method to produce 150 widgets. The least cost method to produce 400 widgets. The earliest point at which the cost will be the same (in units).