1/.1897rockwell hardness of pins of a certain type is known to have a mean of 50 and a standard deviation of 1.2 under regular conditions. without assuming population normality, what is the approximate probability that the sample mean hardness for a random sample of 40 pins is at least 51?

Me its important ! marge runs an ice cream parlor. her speciality is triple chocolate sundaes.she can prepare 1 sundae every 2 minutes, and she earns $1.20 for each sundae she makes . if she just makes sundaes for a single shift of at most 4 hours and at least 2 hours , which function relates her earnings to the number of minutes she works?