18. The standard cost of labour input for Product B is: Two hours of skilled labour paid at 15 per hour Last month 1,000 units of Product B were produced, and the skilled labour cost was 25,300 for 2,700 hours of work. Calculate the total labour variance: (a) 4,000 Favourable (b) 55,700 Adverse (c) 10,300 Adverse (d) 4,700 Favourable