Why are the periodization labels Ancient, Medieval and Modern problematic?

Arandom variable x has a mean of 10 and a standard deviation of 3. if each value of x is multiplied by 2, what will the new mean and standard deviation be?

Evidence suggests that the ancient romans had a very formal medical system. it included which of the following? click all that apply. medical schools universities physician apprenticeships nursing homes hospital facilities

Which of the following characterize the historical move toward urbanization? i. increase in pollution ii. increase in frequency of natural disasters iii. increase in incidence of infectious disease a. i b. ii c. i and ii d. i and iii e. i, ii and iii