During the last 6 weeks, the actual costs of labor for Solsana Company were as follows: Week 1 Week 2 Week 3 $38,500 $40,000 $42,000 Week 4 Week 5 Week 6 $45,600 $48,000 $51,000 The standard materials cost for each week was $40,000 with an allowable deviation of 5,000.

Required: Plot the actual costs over time against the upper and lower limits. Comment on whether or not there is a need to investigate any of the variances.