17. Three mark exercise problems II

1. What is the greatest possible volume of a vessel that can be used to measure exactly the volume of milk in cans (in full capacity) of $80$ litres, $100$ litres and $120$ litres?

 

 

Greatest possible volume $=$ litres

 

2. The traffic lights at three different road junctions change after every $40$ seconds, $60$ seconds and $72$ seconds respectively. If they changed simultaneously together at $8 \ a. m$ at the junctions, at what time will they simultaneously change together again?

 

 

The traffic lights simultaneously change together again After 60 seconds or 1 min,at 8:02 a.mAfter 360 seconds or 6 min,at 8:06 a.mAfter 360 seconds or 6 min,at 8:06 p.mAfter 36 seconds or 0.5 min,at 8:00 a.m