You are hiking to the top of a small canyon. when you stop for a rest you decide to shout “hello” across the canyon. you hear your echo 1.10 s after your shout. if sound waves travel at 340 m/s, how wide is the canyon?

At the speed of 340 m/s , sound travels (1.10 x 340) = 374 meters in 1.10 s .

That's the round-trip distance from my mouth to the other side of the canyon
and back, so the other side of the canyon is  374/2 = 187 meters away. 
(about 614 feet)