Answer:
 Kathleen determines the four arithmetic means to be −2.8 , 1.4, 5.6, and 9.8.
Step-by-step explanation:
The overall interval is 14 -(-7) = 21 units in length. The four equally-spaced "means" divide the interval into 5 equal parts, each one of which is ...
 21/5 = 4.2
The four means are ...
 -7 +4.2 = -2.8
 -2.8 +4.2 = 1.4
 1.4 +4.2 = 5.6
 5.6 +4.2 = 9.8