Final answer:
Greg Chappell should NOT keep the type of surface the same when trying to find out which type of surface has the best rebound bounce.
Step-by-step explanation:
To find out which type of surface has the best rebound bounce, Greg Chappell, the new Indian cricket coach, should NOT keep the type of surface the same. Keeping the type of surface constant would not provide a fair comparison as different surfaces can have different levels of rebound bounce. To conduct a proper experiment, Greg Chappell should vary the type of surface while keeping other factors like the drop height, type of ball, and the measuring scale the same.