Grade 12 Math Problems with Solutions and Answers Grade 12 math problems with detailed solutions are presented. Free Practice for SAT, ACT. and Compass Math tests. Two large and 1 small pumps can fill a swimming pool in 4 hours. One large and 3 small pumps can also fill the same swimming pool in 4 hours. How many hours will it take 4 large and 4 small pumps to fill the swimming pool.