A) 37 s
B) 27 s
C) 24 s
D) 45 s
Correct Answer: C
Solution :
Person?s speed walking only is 1 "escalator" \[\frac{1}{60}\frac{\text{ }\!\!'\!\!\text{ }\!\!'\!\!\text{ escalator }\!\!'\!\!\text{ }\!\!'\!\!\text{ }}{\text{second}}\] Standing the escalator without walking the speed is \[\frac{1}{40}\frac{\text{ }\!\!'\!\!\text{ }\!\!'\!\!\text{ escalator }\!\!'\!\!\text{ }\!\!'\!\!\text{ }}{\text{second}}\] Walking with the escalator going, the speed add. So, the person?s speed is\[\frac{1}{60}+\frac{1}{40}=\frac{15}{120}\]\[\frac{\text{ }\!\!'\!\!\text{ }\!\!'\!\!\text{ escalator }\!\!'\!\!\text{ }\!\!'\!\!\text{ }}{\text{second}}\] So, the time to go up the escalator (?seconds per escalator?) is \[t=\frac{120}{5}=24\]secondYou need to login to perform this action.
You will be redirected in
3 sec