A boy started reading some time between 3 - 4 o'clock. He stopped reading some time between 5-6 o'clock. After reading, he found that the hands of the clock were interchanged. What time did he start reading? What time he completed? how long did he read?

3:25 _5:15 , 1hour 50 min


Sinc the boy started reading between 3-4 0'clock therefore the hour hand should be between 3-4
and the boy stopped reading between 5-6 o'clock therefore the hour hand should be between 5-6
now since the boy found that the hands are interchanged 
then first hour hand was between 3-4 then it is between -6 it is only possible only and only if the minute hand is first between 5-6 
therefore the starting will be 3:25 pm and the stopping time will be  5:15 pm
the total time he read is 1 hour 50 min... 
1 4 1
do you think that at 3:25 pm the hour hand will be exactly at 3??
no not exactly at 3
1 hour and 50 mins is the answer