A factory has estimated its overheads for a year at Rs 96,000. The factory runs for 300 days in a year; it works 8 hours a day. The total budgeted production for the year is 24,000 articles. Actual data are also given as follows for the month of April 1994:

Actual overhead Rs 8,500 Output 2,100 articles Idle time 4 hours Calculate: (1) overhead cost variance, (2) overhead budget variance, (3) overhead efficiency variance and (4) idle time variance.