Mack Trucks decides to conduct an experiment to determine if a new oil additive actually results in increased fuel efficiency. They find a lab that contains 50 engines that are exactly alike. Mack randomly divides the 50 engines into two groups an experimental group (which has the new oil additive)and the control group (which does not have the new oil additive). They pour the exact same amount of fuel into all 50 engines and time how long each engine runs. Afterward, they average the length of time run by the 25 engines in the control group versus the 25 engines in the experimental group. Which of the following represents the experimental design in this study?
A) X 01
B) (R) 01 X 02
(R) 03 04
C) 01 X 02
D) (R) 01 X 02
(R) 03 D 04
E) (R) 01 02
(R)03 D 04

Middle schoolhistory 5+3 pts 1. the pacific islands formed by coral reefs are called (1 point) a. volcanic. b. reefs. c. atolls. d. plates. 2. what is a reason few people have settled in the interior of australia? (1 point) a.no mineral wealth is in the area. b.land is too expensive. c.the area is too dangerous. d.the area has little water and arable land. 3. what was one effect of plate movement on the pacific region? (1 point) a.australia and new zealand became b.connected to north america. c.plate movement isolated many species. few volcanoes formed. d.the regional climate grew much colder. 4. you live on a small island in the pacific ocean. though beautiful, your island has poor soil for farming and few natural resources. you most likely live (1 point) a.on a densely populated island. b.on the south island of new zealand. c.in new guinea on a volcanic island off the coast of australia. d.on a low island. 5. which change would most likely have to take place first to encourage more human settlement in the outback? (1 point) a.the climate would need to get warmer. b.the winters would need to be milder. c.the region would need more fertile land and water d.people would need to build more cities there. 6. what would be an example of how the maori are reclaiming their culture? (1 point) a.learning english b.playing rugby and other sports c.studying maori culture in schools d.learning how to cook asian cuisine 7. what conclusion can correctly be made about british colonization of this area? (1 point) a.the british policies embraced the cultures of the original inhabitants. b.the british disregarded the cultures of the original inhabitants. c.the british had a neutral policy toward native cultures. d.none of the above plz answer these