Problema Solution

A jogger ran 3 miles then decreased her speed by 1mph and ran 4miles. Her total time was 1 3/4 hours.Find her speed for each part of the run. Let x = the speed for the first 3 miles.

Answer provided by our tutors

total time tAKEN =  13/4 hrs

let x = initial speed

and it travell 3 mile in this speed

then travelled 4 miles in x -1 speed

so total distance covered = 3 +4 = 7 miles 

total time taken = 13/4 hrs

so

s = d/t

t = d/s

so 

13/4 = 3/x + 4 / x-1

=> x = 2.2 miles / hrs

so x - 1 = 1.2 miles /hrs answer