Someone pls help I'm genuinely confused I've literally been trying to figure out all three of these for like two hours now but I can't figure it out

2÷6+1/2 to the second power plus one

Find the greatest common factor of -30x 4 yz 3 and 75x 4 z 2.

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.