Bunuel wrote:
How much time does Mr. Richards take to reach his office from home?
(1) One day, he started 30 minutes late from home and reached his office 50 minutes late, while driving 25% slower than his regular speed.
(2) He needs to drive at a constant speed of 25 miles per hour to reach his office just in time if he is 30 minutes late from home.
Tricky question in my opinion.
The fundamental concept here is
Velocity = Distance/Time.
So,
t = regular time to reach Mr. Richard's house from his house (minutes), d = distance from home to office (miles) and V = regular speed (miles per minutes).
(i) t_initial = 30 and t_final =
t + 50.
So, the time requiered is: t_final - t_initial =
t +50 - 30 =
t + 20.
Also we have V_new = d/(
t + 20) --> fundamental relation in the new scenario
On the other hand V_new = 75%*V or 3/4*V, because the velocity is 25% slower than his regular speed
So, V_new = 75%*d/
t = d/(
t + 20) -->
t= 60
Sufficient(ii) V_new = 25 when t_initial = 30 and t_final = t. So, we have 25 = d/(t - 30). d is unknown, so
insufficientThen the correct answer is
(A)Let me know if you have comments or there is something wrong in my post.
Cheers,
R.