At what time between 5.30 and 6 will the hands of a clock be at right angles?

A. 478/11min. past 5
B. 480/11min. past 5
C. 40 min. past 5
D. 45 min. past 5

• B. 480/11min. past 5
  
  using this formula
  Apply the following formula:
  11/2m-30h=90 deg ..... pls note that here h=5
  then 11/2 min = 90 +30*5 = 240
  
  min= 240*2/11 = 480/11 min past 5.... option B
• 12 years agoHelpfull: Yes(10) No(2)
• At 5 o'clock, the hands are 25 min. spaces apart.
  
  To be at right angles and that too between 5.30 and 6, the minute hand has to gain (25 + 15) = 40 min. spaces.
  
  55 min. spaces are gained in 60 min.
  
  40 min. spaces are gained in (60*40/55) min=480/11 min. past 5
  Required time = 480/11 min. past 5.
• 10 years agoHelpfull: Yes(3) No(1)
• The clock will be at right angles when the angle between the hour hand and minute hand is 90 deg.
  Apply the following formula:
  11/2m-30h=90 deg
  (11/2)m-30*11/2=90
  Solving we get m=510/11
  So the clock will be at right angle when the time is 510/11 min past 5(option not given)
• 12 years agoHelpfull: Yes(1) No(9)