The mean weekly income of residents of one state is $570. A random sample of 12 residents of one small town in the state yielded the following weekly income in dollars
480 780 392 431 515 717 1120 495 560 520 503 900
At the 0.05 level of significance, does the data provide sufficient evidence to conclude that the mean weekly income for residents of this town is lower than the state mean income of $570? Assume that the population has a normal distribution