Mary travels the first 9 hours of her journey at 40 mph speed and the remaining 6 hours at 30 mph speed. What is the average speed of Mary's travel in mph? Answers.
A) 32 mph
B) 34 mph
C) 36 mph
D) 35 mph
E) 31 mph
Explanation :   Average speed=Total Distance/Time.   Total distance travelled by mary = Distance covered in the first 9 hours + Distance covered in the next 6 hours.   Distance covered in the first 9 hours = 9Ã—40=360 miles   Distance covered in the next 6 hours= 6Ã—30=180 miles   Therefore, total distance travelled = 360+180= 
<gadget id="calculator">360+180</gadget>
<output>540</output>
540 miles.   The total time taken= 9+6= 
<gadget id="calculator">9+6</gadget>
<output>15</output>
15hours.   Hence, the average speed=540/15= 
<gadget id="calculator">540/15</gadget>
<output>36</output>
36 mph.   Answer : 36 mph
<result>C</result>
Mary travels the first 9 hours of her journey at 40 mph speed and the remaining 6 hours at 30 mph speed. What is the average speed of Mary's travel in mph?