As per an estimate, the depth D(t), in centimeters, of the water in a tank at t hours past 12:00 a.m. is given by $D(t)=-10(t-7)^2+100$ , for $0 \le t \le 12$ .
At what time does the depth of the water in the tank become the maximum?

Correct answer marked below

5:30 a.m.

7:00 a.m.

Correct

7:30 a.m.

8:00 a.m.

9:00 a.m.

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What this question tests

Your ability to evaluate and compose functions, including unusual defined operations.

Applying function operations in the wrong order or ignoring domain restrictions.

As per an estimate, the depth D(t), in centimeters, of the water in a tank at t hours past 12:00 a.m. is given by D(t)=−10(t−7)2+100D(t)=-10(t-7)^2+100D(t)=−10(t−7)2+100, for 0≤t≤120 \le t \le 120≤t≤12. At what time does the depth of the water in the tank become the maximum?