Chapter 8 Rational Functions - Standardized Test Practice - Short Response - Page 611: 14

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Given: $T=\frac{12}{s}+\frac{12}{w-s}$ Plug in $T=9\\w=6$ Then $9=\frac{12}{s}+\frac{12}{6-s}\\9s(6-s)=12(6-s)+12\\9s(6-s)=72\\s(6-s)=8\\6s-s^2=8\\-s^2+6s-8=0\\(s-2)(s-4)=0\\s=2 \lor s=4$ The speed of the elevator is either 2 ft/sec or 4 ft/sec.