Standard Deviation Formula
问题 I have this assignment in which i will show the prompt for it: Write a program that reads in a set of test score data from the user. (Test scores should be entered in decimal form to represent the percentage grade). Once the user has finished entering the test scores (entering -1 will signal the end of input), print out the number of tests entered, the average of the tests, and the standard deviation. Use the following formula (Welford’s method) to calculate the standard deviation: (Standard