The clock has totally gained 16 minutes and 40 sec. i.e. 1000 seconds in 160 hrs. In order to show the right time, the clock has to gain only 6 min i.e. 360 seconds. Just apply the chain rule, the clock gained 1000 sec in 160 hrs, it will gain 360 sec. In 360 × 160/1000 = 288/5 hrs i.e. 57 3/5. Adding 57 hrs & 36 minutes in Monday 5 p.m. you get 2:36 a.m. on Thursday.