During June, the Charleston Manufacturing Company's costing system reported several variances that the production manager was surprised to see. Most of the company's monthly variances are under $125, even though they may be either favorable or unfavorable. The following information is for the manufacture of garden gates, its only product.
(1) Direct materials price variance, $800 unfavorable.
(2) Direct materials efficiency variance, $1,800 favorable.
(3) Direct manufacturing labor price variance, $4,000 favorable.
(4) Direct manufacturing labor efficiency variance, $600 unfavorable.
Provide the manager with some ideas as to what may have caused the efficiency variances