Engineers at an oil refinery find out how easily gasoline evaporates by measuring its vapor pressure. as they make gasoline, they need to determine whether its vapor pressure is high enough. the standard deviation of the vapor pressure of the gasoline made by the refinery is always 0.03 (pounds per square inch). which hypothesis test would be most appropriate for this task?
a. one sample z-test.
b. one sample t-test.
c. paired-samples t-test.
d. two sample t-tes.