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# As per an estimate, the depth D(t), in centimeters, of the water in a

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Math Expert
Joined: 02 Sep 2009
Posts: 50000
As per an estimate, the depth D(t), in centimeters, of the water in a  [#permalink]

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01 Oct 2018, 23:41
00:00

Difficulty:

15% (low)

Question Stats:

76% (01:02) correct 24% (02:05) wrong based on 25 sessions

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

(A) 5:30 a.m.
(B) 7:00 a.m.
(C) 7:30 a.m.
(D) 8:00 a.m.
(E) 9:00 a.m.

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Re: As per an estimate, the depth D(t), in centimeters, of the water in a  [#permalink]

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02 Oct 2018, 00:17
For the Depth to be maximum, $$(t−7)^2$$ (Always Positive) should be minimum. At t=7. Value becomes 0. Then Depth will be 100 Centimeters.

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Re: As per an estimate, the depth D(t), in centimeters, of the water in a &nbs [#permalink] 02 Oct 2018, 00:17
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