Data Sufficiency

On a recent trip, Mary drove 50 miles. What was the average speed at which she drove the 50 miles?

1) She drove 30 miles at an average speed of 60 miles per hour and then drove the remaining 20 miles at an average speed of 50 miles per hour

2) She drove a total of 54 minutes

[spoiler]Answer: A, but I got D. [/spoiler]

IMO D

sparkle6 wrote:On a recent trip, Mary drove 50 miles. What was the average speed at which she drove the 50 miles?

1) She drove 30 miles at an average speed of 60 miles per hour and then drove the remaining 20 miles at an average speed of 50 miles per hour

2) She drove a total of 54 minutes

[spoiler]Answer: A, but I got D. [/spoiler]

u sure the OA is A???????
I think the answer is clearly D.. unless theres some crucial info tht has been missed out in the Q u put up here...
wats the source?[/spoiler]

I got it from a series of worksheets that a friend passed on to me. It has had some mistakes in the past, so I'm guessing this answer also had a mistake.

Clearly the answer is D. I think probably the answer is wrong

Regards,
Chetan

2) She drove a total of 54 minutes --> does not mention whether she drove with uniform speed or not. So, insufficient, IMO.

badpoem wrote:2) She drove a total of 54 minutes --> does not mention whether she drove with uniform speed or not. So, insufficient, IMO.

the question is asking for the average speed over the whole journey. It doesn't matter whether Mary drove at a constant speed or not.

It has to be D

Answer is A.

Statement 2 is insufficient. We don't know whether she drove at a constant speed throughout the trip or not