Part A There are 30 students in a class. 17 of the students are boys. What percent of the class are girls. * Part B If the percentages are the same throughout the grade, how many girls are in the whole seventh grade if there are 150 seventh graders? Please help me answer ;)

Thompson and thompson is a steel bolts manufacturing company. their current steel bolts have a mean diameter of 127 millimeters, and a variance of 36. if a random sample of 35 steel bolts is selected, what is the probability that the sample mean would differ from the population mean by greater than 0.5 millimeters? round your answer to four decimal places.