An investigator drove east at an average speed of 90 kilometers (km) per hour for 3 minutes. During the remaining 100 minutes of her travel, the investigator drove north. If the investigator drove a total of 204.5 km, what was her average speed when traveling north?

Question

Quizplus · Accepted Answer

3 mins = 1/20 hr (60 ÷3); 1/20 x 90 km/hr = 4.5 km traveled in the first 3 minutes; 204.5 km
4.5 km = 200 km remaining. 100 mins = 1 hour and 40 minutes which equals 1 2/3 hrs or 5/3 hrs; speed (rate) for the remaining 200 km = 200 km ÷ 5/3 hrs = 120 km/hr

An Investigator Drove East at an Average Speed of 90