posted by Catherine .
Write the null and alternative hypotheses. Justify which is the claim. A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is less than 900 hours
The claim: mean < 900
other option: mean > or = 900
The null hypothesis is the one with an equal sign...
Your null hypothesis would be mean=900
Your alt. hypothesis would be mean<900
The alt. hypothesis is the claim.