The Next Questions Are Based on the Following Information

Essay

The Next Questions Are Based On The Following Information:
Research and development has designed a ball point pen so that the true average writing lifetime under controlled conditions (involving the use of a writing machine)is at least 12 hours.A random sample of 18 pens is selected,the writing lifetime of each is determined,and a normal probability plot of the resulting data supports the use of a one-sample t test.
-Explain carefully the distinction between null and alternative hypotheses.