A golfer rides in a golf cart at an average speed of 3.93 m/s for 43.3 s. She then gets out of the cart and starts walking at an average speed of 1.13 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 1.99 m/s?

Answer 1

d1 = 3.93m/s * 43.3s = 170.2 m.

d2 = 1.13*T.

r = (d1+d2)/T = 1.99 m/s.
(170.2+1.13T)/T = 1.99.
Multiply by T:
170.2 + 1.13T = 1.99T.
1.99T - 1.13T = 170.2.
0.86T = 170.2.
T = 198 s.

Answer 2

Correction: r = (d1+d2)/(43.3+T) = 1.99.
(170.2+1.13T)/(43.3+T) = 1.99.
Solve for T.