The mean life of a tire is 30,000 km. The standard deviation is 2000 km.
Then, 68% of all tires will have a life between ___________ km and __________ km.
28,000 km and 32,000 km.
24,000 km and 34,000 km.
26,000 km and 34,000 km.
27,000 km and 31,000 km.