Answer:
The accuracy can be improved by making sure no external force is applied, i.e the marbles should accelerate under gravity only during each trial.
Step-by-step explanation:
Accuracy is a term used to describe the relationship between a measured value to the real value. When a measured value is accurate, it implies that there is little or no error in the value; thus it is equal to the real value or very close to it.
Since this experiment is to determine the speed with which the marble roll down the plane, they should ensure uniform acceleration through out the trials. The marbles should be allowed to move under the influence of gravity only without applying any external force.