A new facility has to be designed to do all the welding for 3 products: A,B and (c) Per unit welding time for each product is 20s, 40s and 50s respectively. Daily demand forecast for product A is 450, for B is 360 and for C is 240.A welding line can operate efficiently for 220 minutes a day. Number of welding lines required is
(a) 5 (b) 4 (c) 3 (d) 2