update project1 part1 for step4:This only needs to be done for the specific value of lambda
Merge branch 'master' of https://github.com/gdwangh/coursera-dataScientists-6-Statistical-Inference
update part2, adding summary and plot for assumption that the toothgrowth fit normal distribution
update part1, adding the qqplot for step 3 normal distribution
update part2, adding summary for SD and hist, deleting the assumption of more dose more length