A company that manufactures fluorescent light bulbs claims that the bulbs will operate for 10,000 hours.However engineers, familiar with the production process, used to believe that, on average, the company's light bulbs last for less than 10,000 hours.To test this hypothesis, 50 light bulbs were randomly selected and their lifespans were recorded. The data resulted in a sample mean of 9875 hours. You are interested in whether there is sufficient evidence to conclude that the true mean lifespan of the company's light bulbs is less than 10,000 hours.

What is most appropriate equation that should be used to calculate the test statistic Ho: =10,000 HA: <10,000

z* = x s or z* = pp0 p0(1p0) n or z* = x o s n or t* = ppo po(1po) n

or None of the above are correct.