6. During the construction of a house, six joists of 24 feet each must be trimmed to the correct length of 23 feet. The operations for cutting a joist involve the following sequence:

1.~

Operation 1. Place joist on saw horses 2. Measure correct length (23 feet)

3. Mark cutting line for circular saw 4. Trim joist to correct length 5. Stack trimmed joist in a designated area Time (seconds)

15 5

5 20 20 1.2 Three persons are involved: Two loaders must work simultaneously on operations 1,2, and 5, and one cutter handles operations 3 and 4. There are two pairs of saw horses on which untrimmed joists are placed in preparation for cutting, and each pair can hold up to three side-by-side joists. Suggest a good schedule for trimming the six joists.