In an experiment to learn if substance M can help restore memory, the brains of 20 rats were treated to damage their memories. The rats were trained to run a maze. After a day, 10 rats were given M and 7 of them succeeded in the maze; only 2 of the 10 control rats were successful. The plus four 90% confidence for the difference between the proportion of rats that succeed when given M and the proportion that succeed without it is
Answer
a. 0.417 +/- 0.185
b. 0.417 +/- 0.304
c. 0.455 +/- 0.312
d. 0.455 +/- 0.312