Answer:
Dr. Gavin needs to recruit 200 participants.
Step-by-step explanation:
Dr. Gavin is conducting a 2 x 4 independent-groups factorial design.
This means that there will be 2*4 = 8 cells.
Assuming he wants 25 people in each cell, how many participants does Dr. Gavin need to recruit?
25 people in each cell, 8 cells. So
25*8 = 200
Dr. Gavin needs to recruit 200 participants.