In a particular statistics exam, the 35th percentile of final exam score is 42, and the 70th percentile of final exam score is 76. A histogram of the scores approximately follows the normal curve. What is the approximate standard deviation of the final exam scores? Hints: What is the z value in the normal table that gives you closest to 35% of the area between -z and z? Now what does that tell you about the number of SDs in between 42 inches and 76 inches? You might find it helpful to draw a picture of the normal curve with original units and standard units. O 7.5 O 37.8 O 20.7 O 13.1