Final answer:
The value of the margin of error (MOE) when it equals a value of E is 0.5E.
Step-by-step explanation:
The margin of error (MOE) is the quantity that we add and subtract from the sample mean to obtain the confidence interval.
When MOE equals a value of E, the margin of error would be equal to half of E.
Therefore, the value of the margin of error would be 0.5E.