D=546m. r=1.3m/sec. 546m=1.3m/sec(t).
546m divided by 1.3m/sec = t = 420 sec (the meters will cancel out, leaving the answer to just seconds).
420 seconds divided by 60sec/min = 7 minutes.
Answer:

Step-by-step explanation:
let distance between farmhouse and road is 2 km
From diagram given
p is the distance between road and past the intersection of highway
By using Pythagoras theorem

differentiate wrt t
we get




putting p = 3.7 km

