Hello I need someone to help me with a math problem from Kahn academy

When i add money am i supposed to make it like this 7+12 or 7.00+12.00 because i got 19 dollars for my 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.

Hormones perform important functions within the reproductive system. during puberty, a number of changes occur in the body. which hormone is responsible for the development of these characteristics in the female? estrogen progestin progesterone testosterone