hamburger menu
All Coursesall course arrow
adda247
reward-icon
adda247
    arrow
    arrow
    arrow
    How many times are the hour and the minute hands of a clock at a right angle in a period of two days?
    Question

    How many times are the hour and the minute hands of a clock at a right angle in a period of two days?

    A.

    88

    B.

    48

    C.

    92

    D.

    77

    Correct option is A

    Concept: The minute hand covers 360° in an hour and 6° in a minute.
    The hour hand covers 30° in an hour and 0.5° in a minute.
    Solution:
    Starting from midnight i.e. 12 o'clock at midnight, the first time the difference between the two hands would be 90° is:
    6x = 0.5x + 90° (x is the number of minutes)
    => 5.5x = 90°
    => x = 180/11 minutes
    The next time the difference between the two hands would be 90° is when the minute hand would have moved 180° away from the hour hand or the difference between both hands would have been 270°.
    6x = 0.5x + 270
    => 5.5x = 270
    => x = 540/11 minutes
    Thus, the difference between two consecutive moments where both hands form a right angle is:
    540/11 - 180/11 = 360/11 minutes
    Thus, the two hands form a right angle after every 360/11 minutes.
    Total number of minutes in a day = 24 × 60 = 1440 minutes.
    Number of times the two hands will form a right angle in a day = 1440 ÷ (360/11)
    => (1440 × 11) ÷ 360
    => 4 × 11 = 44 times
    So, hour and the minute hands of a clock at a right angle in a period of two days: 

    44×2=8844\times2 = 88 
    Thus, correct option is (a).

    Free Tests

    Free
    Must Attempt

    CBT-1 Full Mock Test 1

    languageIcon English
    • pdpQsnIcon100 Questions
    • pdpsheetsIcon100 Marks
    • timerIcon90 Mins
    languageIcon English
    Free
    Must Attempt

    RRB NTPC Graduate Level PYP (Held on 5 Jun 2025 S1)

    languageIcon English
    • pdpQsnIcon100 Questions
    • pdpsheetsIcon100 Marks
    • timerIcon90 Mins
    languageIcon English
    Free
    Must Attempt

    CBT-1 General Awareness Section Test 1

    languageIcon English
    • pdpQsnIcon40 Questions
    • pdpsheetsIcon30 Marks
    • timerIcon25 Mins
    languageIcon English
    test-prime-package

    Access ‘RRB Group D’ Mock Tests with

    • 60000+ Mocks and Previous Year Papers
    • Unlimited Re-Attempts
    • Personalised Report Card
    • 500% Refund on Final Selection
    • Largest Community
    students-icon
    354k+ students have already unlocked exclusive benefits with Test Prime!
    Our Plans
    Monthsup-arrow