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6

Part of 2022 Girls in Math at Yale

Problems(1)

Girls in Math at Yale 2022 Problem 6: in which Carissa doesn't get hit by a car

Source:

2/27/2022
Carissa is crossing a very, very, very wide street, and did not properly check both ways before doing so. (Don't be like Carissa!) She initially begins walking at 22 feet per second. Suddenly, she hears a car approaching, and begins running, eventually making it safely to the other side, half a minute after she began crossing. Given that Carissa always runs nn times as fast as she walks and that she spent nn times as much time running as she did walking, and given that the street is 260260 feet wide, find Carissa's running speed, in feet per second.
Proposed by Andrew Wu
Yalecollege