Answer:
68% of all tires will have a life between 28,000 km and 32,000 km.
Explanation:
Given:
Mean life (μ) = 30,000 km
The standard deviation (σ) = 2000 km
The standard deviation of datasets which have normal distribution can be used to determine the proportion of values that lie within a particular range of the mean value. This follows Empirical rule:
68% of the values in the dataset will lie in area covered between Mean – 1 Standard Deviation and Mean + 1 Standard Deviation
Mean – 1 Standard Deviation = 30,000 -1(2000)= 30000-2000
Mean – 1 Standard Deviation = 28,000km
Mean + 1 Standard Deviation = 30000 + 1(2000) = 30000+2000
Mean + 1 Standard Deviation = 32,000km
68% of all tires will have a life between 28,000 km and 32,000 km.