Hello, mmattson07!

This was trickier than I thought . . .

For convenience, assume that the distance from San Antonio to Houston is 1314 km.You drive on Interstate 10 from San Antonio to Houston,

half thetimeat 73 km/h and the other half at 90 km/h.

On the way back you travel half thedistanceat 73 km/h and the other half at 90 km/h.

(a)What is your average speed from San Antonio to Houston?

We drove km at 73 mph.

. . This took: . hours.

We drove the other km at 90 mph.

. . This took: . hours.

These two times are equal: . km.

We drove 588.48 km at 73 km/hr.

. . This took: . hours

We drove the other: . km at 90 km/hr.

. . This took: . hours. .(Of course!)

We drove 1314 km in 16.12 hours.

From San Antonio to Houston, we averaged: . km/hr.

(b) What is your average speed from Houston back to San Antonio?

We drove 657 km at 73 km/hr,

. . This took: . hours.

We drove 657 km at 90 km.hr.

. . This took: . hours.

We drove 1314 km in 16.3 hours.

From Houston to San Antonio, we averaged: . km/hr.

(c) What is your average speed for the entire trip?

We drove a total of 2628 km in a total of 32.42 hours.

For the entire round trip, wel averaged: . km/hr.