One of the two buses completes a journey of 300 miles in 7 1/2 hours and the other journey of 450 miles in 10 hours. the ratio of their average speed is
Choose the correct option:	A) 2:3	B) 4:5	C) 3:4	D) 8:9	E) 5:6
300 miles completed in 7 1/2 hours means 27000 sec   450 miles completed in 10 hours means 36000 sec   speed=distance/time   1st bus speed:2nd bus speed=300/27000:450/36000=10/9:5/4=40:45=8:9   ANSWER:8:9
<result>D</result>
One of the two buses completes a journey of 300 miles in 7 1/2 hours and the other journey of 450 miles in 10 hours. the ratio of their average speed is