A light-bulb manufacturer advertises that the average life for ...

[plus1]

A light-bulb manufacturer advertises that the average life for its light bulbs 900 hours. A random sample of 15 of its light bulbs resulted in the following lives in hours.
 
  995 590 510 539 739 917 571 555
   916 728 664 693 708 887 849
  At the 10 significance level, do the data provide evidence that the mean life for the company's light bulbs differs from the advertised mean?

Question 2

Draw a normal distribution and identify the mean of x on the distribution. Discuss the symmetry and the total area under the curve. What is the probability that a value of x will be greater than the mean?
 
  What will be an ideal response?

[mathjasmine]

Answer to Question 1

Test statistic: t = -4.342. Critical values: t = 1.761. Reject :  = 900 hours. There is sufficient evidence to support the claim that the true mean life differs from the advertised mean.

Answer to Question 2

The diagram should be a bell-shaped distribution with its mean at the center of the horizontal axis. The total area under the curve is 1, and the probability that the value of x is greater than the mean is 0.5.

[plus1]

Excellent

[FergA]

Thanks for the timely response, appreciate it