arjtryarjtry wrote:

It took the bus 4 hours to get from town A to town B. What was the average speed of the bus for the trip?

1.In the first 2 hours the bus covered 100 miles

2.The average speed of the bus for the first half of the distance was twice its speed for the second half

average speed = total distance / total time = d/4

so we have to find out d

statement 1 : we dont know the distance the bus covered in second two hours.. not suff

statement 2 : d/(2t1) = 2d/(2t2)

t2 = 2t1

we know t1+t2 = 4

so t1 = 4/3

and t2 = 8/3

still we cant find d ... so not suff

combine two statements

distance covered in 2 hours = distance covered in t1 (4/3) hours + distance covered in (2-4/3) hours

100 = d/2 + d/(2t2) * (2-4/3)

100 = d/2 + 3d/(2*8) * ((6-4)/3)

100 = d/2 + d/8

suff... actually no need to solve it. we know we can find d and the average speed.... Option C