Acompany wants to compare two washing detergents (brands a and b) to see which best keeps colors from fading. twenty new, identical red t-shirts will be used in the trials. ten t-shirts are washed 15 times with brand a in warm water. the other 10 t-shirts are washed with brand b in cold water. the amount of fading is rated on a 0 to 100 scale, and the mean for the t-shirts washed in brand a is compared to the mean for the others. is this a good experimental design?
(a) no, because the means are not the proper statistics for comparison. (b) no, because more than two brands of detergent should be used.
(c) no, because more temperatures of water should be used.
(d) no, because water temperature is confounded with brand of detergent. (e) yes.