The items below are based on the following scenario. An experimental psychologist interested in whether the color of an animal's surroundings affects learning rate tests 16 rats in a box with colorful wallpaper. The average rat of this strain can learn to run this type of maze in a box without any special coloring in 25 trials, with a variance of 64 and the distribution is normal. The mean number of trials to learn the maze for the rats tested with the colorful wallpaper is 11. What is the null hypothesis?