You drive for 30 min at 100 km/h and then stop for 15 min.You then drive for 45 min at 80 km/h.Your average speed for the entire trip is
A)73 km/h.
B)83 km/h.
C)88 km/h.
D)90 km/h.
E)97 km/h.

Question

Quizplus · Accepted Answer

The total distance driven is the sum of the distances covered in each segment: $30 \text{ min} \times \frac{100 \text{ km}}{60 \text{ min}} + 45 \text{ min} \times \frac{80 \text{ km}}{60 \text{ min}} = 50 \text{ km} + 60 \text{ km} = 110 \text{ km}$. The total time is $30 \text{ min} + 15 \text{ min} + 45 \text{ min} = 90 \text{ min} = 1.5 \text{ hours}$. The average speed is $\frac{110 \text{ km}}{1.5 \text{ hours}} = 73.33 \text{ km/h}$, which rounds to 73 km/h.

You Drive for 30 Min at 100 Km/h and Then