WBCS.LIVE practice question

At what exact time between 4 o'clock and 5 o'clock will the hands of a clock be at a right angle (90 degrees)?

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 38 and 2/11 minutes past 4
  2. 40 minutes past 4
  3. 35 and 5/11 minutes past 4
  4. 43 and 7/11 minutes past 4

Correct answer and explanation

Correct answer: 38 and 2/11 minutes past 4

Explanation: ✅ Correct Answer: A) 38 and 2/11 minutes past 4 📚 Explanation: At 4 o'clock, the minute hand is 20 minute-spaces behind the hour hand. A right angle equates to a gap of 15 minute-spaces. This happens twice: when the minute hand is 15 spaces behind, and 15 spaces ahead. To be ahead, the minute hand must gain (20 + 15) = 35 spaces. Time taken = 35 × (12 ÷ 11) = 420 ÷ 11 = 38 and 2/11 minutes past 4.