Rachel uses an experimental research design to investigate whether a new physical exercise program improves motor skills in people with Parkinson's disease. In the control group, 305 of participants improved their motor skills after 1 month. In the group participating in the new physical exercise program, 45% of participants improved their motor skills after 1 month. Rachel's analyses find that the observed difference in motor skills improvement between the two groups is very unlikely if the null hypothesis is true. State the null hypothesis for this study. Explain how type I error may be responsible for Rachel's conclusion.|