Create a Python program that accepts a string. The program should return a string, with each character in the original string doubled. If the user inputs "now", it should return "nnooww," and if you input "123a!", it should return "112233aa!!".

The output voltage of a power supply is assumed to be normally distributed. sixteen observations are taken at random on voltage are as follows: 10.35, 9.30, 10.00, 9.96, 11.65, 12.00, 11.25, 9.58, 11.54, 9.95, 10.28, 8.37, 10.44, 9.25, 9.38, and 10.85