Saturday

January 31, 2015

January 31, 2015

Posted by **michelle** on Sunday, July 31, 2011 at 10:12pm.

54 months with a standard deviation of 6 months. We take a random sample of 50 batteries.

a. Find the probability that their mean life is less than 52 months.

b. Find the probability that their mean life is more than 53 months.

- stats -
**PsyDAG**, Monday, August 1, 2011 at 3:44pmZ = (mean1 - mean2)/standard error (SE) of difference between means

SEdiff = √(SEmean1^2 + SEmean2^2)

SEm = SD/√(n-1)

If only one SD is provided, you can use just that to determine SEdiff.

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores.

**Answer this Question**

**Related Questions**

Statistics - the manufacturer of a certain brand of auto batteries claims the ...

Math - LongLast Inc. produces car batteries. The mean life of these batteries ...

Statistics - . A certain company makes 12-volt car batteries. After many years ...

Statistics - A certain company makes 12-volt car batteries. After many years of ...

science - Shown below are the data giving the length of life of lights in an ...

Statistics - Shown below are the data giving the length of life of lights in an ...

Statistics - Hi! I've been stuck on this question for a while. I know that I ...

statistics - A manufacturer wishes to estimate the reliability (in months) of a ...

statistics - The Acme Company has developed a new battery. The engineer in ...

Stats - The lifetime of a particular type of battery is normally distributed ...