4. ABC Manufacturing Co. implemented standard costing for its production process. During the month, the company produced 10,000 units, incurring direct materials costs of $150,000 and direct labor costs of $100,000. The standard costs for materials and labor were $15 per unit and $10 per unit, respectively. Calculate the direct materials price variance, direct materials quantity variance, direct labor rate variance, and direct labor efficiency variance. Provide an analysis of each variance and potential causes.