(3) A chief in a restaurant was experiencing difficulty in getting brands of pasta to be "al dente", that is cooked enough so as not to feel starchy or hard but still feel firm when bitten into. Two brands were selected, American and Italian and cooked at different times. The results for two replicates of each type of pasta and cooking time are as follow. Fill in the gaps. Cooking Times (in mins) 4 8 Type of Pasta American 265 310 270 320 269 319 Italian 250 300 245 305 246 301 (a) r = - (b) n' = _ ( c ) X =. (d) X1. = (e) dfT = (f) dfe =