Develop the Null and Appropriate Hypotheses That Are Most Appropriate

Develop the null and appropriate hypotheses that are most appropriate for each of the following situations:
a. A meteorologist claims that the average high temperature for the month of August in Montreal is 27°C. If the residents of Montreal do not believe this to be true, what hypotheses should they test?
b. A car manufacturing plant is acting in accordance with the public's interest in making cars that have fuel consumption of at most 8.2 litres per 100 km. The supervisor will let the cars off the manufacturing floor only if the fuel consumption is less than 8.8 L/100 km. What hypotheses should the plant test?
c. A spokesperson for the Health Department reports that a fish is unsafe for human consumption if the polychlorinated biphenyl (PCB) concentration exceeds 5 ppb. The Carlson family is interested in the mean PCB concentration in a fish from the lake on which they live. What hypotheses should they test?
d. An Internet survey revealed that 50% of Internet users received more than 10 email messages per day. A similar study on the use of email was repeated. The purpose of the study was to see whether use of email has increased.