A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?
Pick one.
A) 15 minutes  B) 25 minutes  C) 1 hour 15 minutes  D) 1 hour 40 minutes  E) 4 hours 30 minutes
Trains depart from X at 6/7/8/9 and reach Y at 7:45/8:45/9:45 etc   Trains depart from Y at 9/9:30/10/10:30 etc. This means a minimum wait of 15 mins is required at Y.   They arrive at Z at 11:20/11:50/12:20/12:50. They depart from Z at 8/8:45/9:30/10:15/11/11:45/12:30 and so on. Note that if she arrives at Z at 20 mins past the hour, she will need to wait for at least 10 mins for 12:30/3:30 etc train. If she arrives at 50 mins past the hour, again she needs to wait for at least 10 mins to take the 2 o clock train. So anyway 10 mins at Z is a given.   So minimum she will need to wait for  15+10= 
<gadget id="calculator"> 15+10</gadget>
<output>25</output>
25 mins.   This works out if she takes 8 o clock train from X, reaches Y at 9:45, takes 10 o clock train from Y and reaches Z at 12:20 and takes 12:30 train from Z.   Answer (25 minutes)
<result>B</result>
A woman is planning a trip that involves 3 connecting trains that depart from Stations X, Y, and Z, respectively. The first train leaves Station X every hour, beginning at 6 a.m., and arrives at Station Y 1(3/4) hours later. The second train leaves Station Y every half hour, beginning at 9 a.m., and arrives at Station Z 2(1/3) hours later. The third train leaves Station Z every 45 minutes, beginning at 8 a.m. What is the least total amount of time the woman must spend waiting between trains if all trains depart and arrive on schedule, and if she arrives at Station Z no later than 3:30 p.m.?