The average typing speed N (in words per minute) after t weeks of lessons is modeled by $N = \frac { 91 } { 1 + 7.5 e ^ { - 0.15 t } }$ . Find the rate at which the typing speed is changing when t = 20 weeks. Round your answer to two decimal places.
A)2.40 words/min/week
B)2.70 words/min/week
C)3.71 words/min/week
D)4.93 words/min/week
E)6.24 words/min/week

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The Answer of The average typing speed N (in words per minute) after t weeks of lessons is modeled by $N = \frac { 91 } { 1 + 7.5 e ^ { - 0.15 t } }$ . Find the rate at which the typing speed is changing when t = 20 weeks. Round your answer to two decimal places.
A)2.40 words/min/week
B)2.70 words/min/week
C)3.71 words/min/week
D)4.93 words/min/week
E)6.24 words/min/week

The Average Typing Speed N (In Words Per Minute) After N=911+7.5e−0.15tN = \frac { 91 } { 1 + 7.5 e ^ { - 0.15 t } }N=1+7.5e−0.15t91​

The Average Typing Speed N (In Words Per Minute) After $N = \frac { 91 } { 1 + 7.5 e ^ { - 0.15 t } }$