Johnson's algorithm yields us an even better solution 14.92 units!

	Name	Job	Processing Time	Machine
Task 1:	Pink	4.26	1
Task 2:	Pink	2.6	2
Task 3:	Pink	4.24	3
Task 4:	Purple	3	1
Task 5:	Purple	1.2	2
Task 6:	Purple	2.04	3
Task 7:	Green	4.44	1
Task 8:	Green	2.96	2
Task 9:	Green	4.24	3