A Researcher Hypothesizes That People of Personality Type K Score

Multiple Choice

A researcher hypothesizes that people of personality type K score higher than people of personality type R on an intelligence test. The S_Difference turned out to be .9, while the mean score of type K people was 18.8 and the mean score for type R people was 21.3. What is the t score?

A) t = (18.8-21.3) / .9² = -3.09
B) t = (18.8-21.3) (.3) = 8.33
C) t = (18.8-21.3) / .9 = -2.78
D) t = (18.8-21.3) / [(2) (.9) ] = -1.39