A manufacturer of car batteries claims that the distribution of the life spans of its best battery has mean 54 months and standard deviation 6 months. A consumer group purchases a random sample of 50 u8batteries and tests the battery life spans. The sample mean lifespan is 52 months.

Assuming the manufacturer’s claim is true, what is the approximate probability of observing a sample mean of 52 months or less?

Assuming the manufacturer’s claim is true, what is the approximate probability of observing a sample mean of 52 months or less?