OA is A. But i don't agree. pls explain

Hi,
Avg speed = Total Distance(d)/Total time taken(t)
Given that t = 3 hours
From(1):
In 1 hour it traveled at 60km/hr.
So, distance in 1 hour is 1*60 = 60km
This is 1/3 of total distance.
So, d/3 = 60 =>d = 180
Given t=3 hrs.
So, avg sped = 180/3 = 60km/hr
Sufficient
From(2):
We can calculate distance traveled by the bus from 1 hour to 3 hours. But, we do not know the distance traveled by bus n the first hour
Not sufficient

Hence, A

what i don't understand is why you assume that other 2/3 part of the road is also gone in 60 kmh (each 1/3)?

blaster wrote:what i don't understand is why you assume that other 2/3 part of the road is also gone in 60 kmh (each 1/3)?

Hi,
I didn't make any assumption. I have calculated the distance for the first 1 hour as we know the speed for 1st hour.
This distance is given as 1/3 of total distance in statement(1). So, total distance will be 3 times the calculated distance.
In the premise, it is given it takes 3 hours. So, to calculate avg. speed, I just divided the total distance with total time(3 hours).

if it took a bus three hours to get from town A to B ,what was the average speed of the bus for the entire trip?
1) During the first hour the bus finished 1/3 of the distance going 60 kmh.

a 60 = 1/3 * total distance
thus total distance = 180. total time = 3 hrs hence average speed = 60km/hr. sufficient,

b no mention about the distance in 1st hour.not sufficient.

A it is.

I agree with answer choice A, and that statement 2 is insufficient, but doesn't it contradict statement 1?

Statement 1 says that for 1 hour, the bus travels at 60km/hr. 1hr * 60km/hr = 60km. It says that this is 1/3 of the total distance traveled. 60km * 3 = 180km total distance.

Statement 2 says that for the second hour, the bus travels at 120km/hr. 1 hr * 120km/hr = 120km. It also says that it travels at half that speed for the third hour. 1 hr * 120/2 km/hr = 60km.

Distance from hour 2 + distance for hour 3 = 180km, the same distance that the first statement says is equal to the total distance, which would make the distance traveled in the first hour 0km/hr.

Data sufficiency statements should never give differing information. What am I missing here?