Answer: D. The probability of a time from 75 seconds to 250 seconds.
Explanation:
We know that a density curve graph for all of the possible values from a to b can be used to find the the probability of the values from a to b .
Given: A density graph for all of the possible times from 50 seconds to 300 seconds.
Then it can be used to find the the probability of a time in the range from 50 seconds to 300 seconds.
From all the given option only option D gives the interval which is lies in the above range.
i.e A density graph for all of the possible times from 50 seconds to 300 seconds can be used to determine the probability of a time from 75 seconds to 250 seconds.