gmatnmein2010 wrote:Bob and Wendy planned to walk from their home to a restaurant for dinner together. However, Bob was delayed at work, and Wendy left for the restaurant before Bob did. If the restaurant is 3 miles from their home and Bob left for the restaurant a half-hour after Wendy did, how long did Wendy have to wait for Bob at the restaurant?

(1) Wendy walked at a constant pace of 4 miles per hour

(2) Bob walked at a constant pace of 1 mile per hour faster than Wendy.

1) is not sufficient - we do not know the speed of Bob
2) is not sufficient - we do not know the speed of Wendy

Together we know the speed of Wendy y, Speed of Bob x
Wendy takes = 45 minutes to reach, bob takes 36 minutes , bob started 30 minutes late ..

Sufficient to calculate the waiting time

gmatnmein2010 wrote:Bob and Wendy planned to walk from their home to a restaurant for dinner together. However, Bob was delayed at work, and Wendy left for the restaurant before Bob did. If the restaurant is 3 miles from their home and Bob left for the restaurant a half-hour after Wendy did, how long did Wendy have to wait for Bob at the restaurant?

(1) Wendy walked at a constant pace of 4 miles per hour

(2) Bob walked at a constant pace of 1 mile per hour faster than Wendy.

from q t=3/B+1/2-3/W
where t is the waiting time for Wendy, B is the Bob's rate and W is the Wendy's rate.

hence in order to know t we require B and W

s1)b=? not given
insuff

s2)B=W+1
INSUFF AS WE DNT KNW W

Together
suff
as we have W and B

gmatnmein2010 wrote:Bob and Wendy planned to walk from their home to a restaurant for dinner together. However, Bob was delayed at work, and Wendy left for the restaurant before Bob did. If the restaurant is 3 miles from their home and Bob left for the restaurant a half-hour after Wendy did, how long did Wendy have to wait for Bob at the restaurant?

(1) Wendy walked at a constant pace of 4 miles per hour

(2) Bob walked at a constant pace of 1 mile per hour faster than Wendy.

ST.1 Wendy walked at a constant pace of 4 miles per hour so time taken by him = 3/4 = 45 minutes but nothing abt bob ==insufficient

St.2 Bob walked at a constant pace of 1 mile per hour faster than Wendy ... but we don't know the exact speed of both for time calculation =========insufficient

combined: speed of Bob = 4+1 = 5 miles per hour .... so, time taken by him = 3/5 = 36 minutes...
so wendy left half an hour earlier
Ans C
so he has to wait = 30 +45 -36 = 75 -36 = 39 minutes.. sufficient .