Final answer:
The average speed for the motorist traveling from town A to town B is calculated by dividing the total distance (145 km) by the total time (3.75 hours), which comes out to be approximately 39 km/h. The closest given option is 40 km/h.
Step-by-step explanation:
To find the average speed of a motorist who travels from town A to town B, we use the formula for average speed, which is the total distance traveled divided by the total time taken for the journey. In this case, the motorist travels 145 km in 3 hours and 45 minutes. To calculate the speed, we first need to convert the time into hours, which is 3.75 hours (since 45 minutes is three-quarters of an hour). Now, we can calculate the average speed:
average speed = distance / time = 145 km / 3.75 hours = 38.67 km/h
So, we round this to the nearest whole number, and the average speed is approximately 39 km/h, which is not listed in the options provided. However, since we must choose the closest option, we select 40 km/h (option b).