At what time between 5.30 and 6 will the hands of a clock be at right angles? Choose the correct option
A) 40 min. past 5
B) 42 min. past 5
C) 43 4/11 min past 5
D) 43 7/11 min. past 5
E) None
Sol.   At 5 o’clock, the hands are 24 min. spaces apart.   To be at right angles and that too between 5.30 and 6, the minute hand hasto gain  (25 + 15)= 
<gadget id="calculator"> (25 + 15)</gadget>
<output>40</output>
40 min. spaces.   55 min. spaces are gained in 60 min.   40 min. spaces are gained in [60/55 * 40] min.= 43 7/11 min.   ∴ Required time = 43 7/11 min. past 5.   Answer 43 7/11 min. past 5
<result>D</result>
At what time between 5.30 and 6 will the hands of a clock be at right angles?