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Finding the Margin of Error Given an Interval: Vehicle Speed

APSTAT-DY8EWN

A $95\%$ confidence interval for a car's average speed (mph) on West Street is $(30,40)$.

From this interval, what is the margin of error for the car's average speed (in mph)?

A

$5$ mph

B

$10$ mph

C

$35$ mph

D

$70$ mph

E

It cannot be determined from the information given.