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Home Aptitude Height and Distance See What Others Are Saying!
  • Question
  • A man on the top of a vertical towers observes a car moving at a uniform speed coming directly towards it. if it takes 12 minute for the angle of depression to change from 30° to 45°, how soon after this will the car reach the tower?


  • Options
  • A. 14 min 20 sec.
  • B. 15 min 22 sec.
  • C. 16 min.
  • D. 16 min 23 sec.

  • Correct Answer
  • 16 min 23 sec. 

    Explanation

    Let us draw a figure below from given question.
    Let AB = h meter be the height of the tower B and C are two points such that ?ACB = 30° ?ADB = 45° and CD = x meter (say)
    From right triangle ABD,
    tan 45° = h/BD
    ? BD = h meter;
    Again from right triangle ABC
    tan 30° = h/(h + x )
    ? h + x = ?3 h
    ? x = (1.73 - 1)h = 0.73h
    Now, 0.73h meter covered in 12 min
    Hence, h meter covered in 12/0.73 = 1200/73 min = 16 min 23 sec .


  • More questions

    • 1. 
      0.0169 / 0.013=?

    • Options
    • A. .13
    • B. .013
    • C. 1.3
    • D. 13
    • Discuss
    • 2. 
      Two posts are x meter apart and the height of one is double that of the other. If from the midpoint of the line joining their feet, an observer finds the angular elevations of their tops to be complementary, then the height (in meter) of the shorter post is :

    • Options
    • A. x 2 ?2
    • B. x 4
    • C. x ?2
    • D. x ?2
    • Discuss
    • 3. 
      If p/q =4/5, then the value of 4/7 + {(2q - p) / (2q + p)} is?

    • Options
    • A. 3 / 7
    • B. 34
    • C. 1
    • D. 2
    • Discuss
    • 4. 
      What is 25% of 25% is equal to?

    • Options
    • A. 6.25
    • B. .625
    • C. .0625
    • D. .000625
    • Discuss
    • 5. 
      The number .05 is hoe many percent of 20?

    • Options
    • A. 25
    • B. .025
    • C. .25
    • D. 2.5
    • Discuss
    • 6. Find the lowest common multiple of 24, 36 and 40.

    • Options
    • A. 120
    • B. 240
    • C. 360
    • D. 480
    • Discuss
    • 7. 
      8 1/ 3% expressed as a fraction is?

    • Options
    • A. 25/3
    • B. 3/25
    • C. 1/12
    • D. 1/4
    • Discuss
    • 8. 
      .025 in terms of term of rate per cent is?

    • Options
    • A. .25%
    • B. 2.5%
    • C. 0.25%
    • D. 371/2%
    • Discuss
    • 9. 
      What percentage of 2/7 is 1/35?

    • Options
    • A. 2.5%
    • B. 10%
    • C. 25%
    • D. 20%
    • Discuss
    • 10. 
      A sum of ? 4000 is lent out in two parts, one at 8% simple interest and other at 10% simple interest. If the annual interest is ? 352, the sum lent at 8% is

    • Options
    • A. ? 1600
    • B. ? 2400
    • C. ? 1800
    • D. ? 2800
    • Discuss


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