A scientist estimates that the mean nitrogen dioxide level in the city is greater than 23 parts per billion. To test this ...

     A   scientist estimates that the mean nitrogen dioxide level in the city is   greater than 23 parts per billion. To test this estimate, you need to   determine the nitrogen dioxide level for 31 randomly selected days. The   results(in parts per billion are listed below. At a=0.06, can you support the   scientist's estimate?