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CDS Elementary Mathematics Test 278
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CDS Elementary Mathematics Test 278
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  • Question 1/20
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    ABC is an equilateral triangle. The side BC is trisected at D such that BC = 3 BD . What is the ratio of AD2 to AB2?
    Solutions

    Let side = x

    Draw

    As triangle ABC is equilateral triangle.

    BE =

    BD =

    DE = BE – BD =

    In triangle ADE by Pythagoras theorem

     =

  • Question 2/20
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    Consider the following statements :

    1) The diagonals of a trapezium divide each other proportionally.

    2) Any line drawn parallel to the parallel sides of a trapezium divides the non-parallel sides proportionally.

    Which of the above statements is/are correct?

    Solutions

    Given :

    A trapezium ABCD in which ABDC and its diagonals AC and BD intersect at O.

    Construction :

    Through O, draw EOAB, meeting AD at E.

    Proof :

    In ADC, EODC

    Therefore,

    ……………..(1)

    In DAB,EOAB

    Therefore,

     ..........(2)

    From 1 and 2, we get,

    Hence, We can say that The diagonals of a trapezium divide each other proportionally.

    Consider second statement :

    Here, ABCD is a trapezium such that EF||AB||DC

    Join EF to cut AC at G.

     , EG||DC , so by basic proportionality theorem , we have

    ………………(1)

     , GF||AB , so by basic proportionality theorem , we have

    ………………(2)

    From (1) and (2)

    Hence, we can say that Any line drawn parallel to the parallel sides of a trapezium divides the non-parallel sides proportionally.

    Hence, both the statements are true.

  • Question 3/20
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    If the roots of quadratic equation  are negative and reciprocal of each other. Then the correct option is-
    Solutions

    Assuming roots of the equation  are  and .

    Then product of roots =

  • Question 4/20
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    A big sized football of radius ‘r’ when kicked up in the air subtends an angle  at the eye of the observer, while the angle of elevation of its center is . Find the height of the center of football.
    Solutions

    In triangle BOD,

    In triangle OAB,

    =

    Hence option d is the correct answer.

  • Question 5/20
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    A string is cut into two parts such that the ratio of the lengths of the complete string and the smaller part is 20 times the ratio of the lengths of the smaller part and the larger part. Find the ratio of the length of the string and the square of the length of the smaller part if the longer part is 4cm.
    Solutions

    Let the length of the smaller part becm and the length of the string becm.

    Larger part = 4cm

    Given that

  • Question 6/20
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    Wages for 40 women for 30 days are Rs.21,600. How many men must work for 25 days to earn Rs.14,400 if the daily wages for a man is double that of woman?
    Solutions

    Wages for 40 women for 30 days = Rs.21,600

    Wages for 1 women for 1 day.

    But the daily wages for a man is double that of woman.

    Hence Wages of man

    Number of men

    Hence 16 men are required to complete the work in the given frame.

  • Question 7/20
    1 / -0

    Three taps A, B and C can together fil the tank in 3 hours. After 1 hour C is closed and the tank is filled in 4 more hours. Find the time in which C alone can fill the tank.
    Solutions

    Three taps A,B and C can together fill the tank in 1 hour

    Remaining part of the tank

    Since C tap is closed so the amount of work needed to be done by (A+B) =

    But it has taken them 4 hours to do so.

    Hence A and B can together fill the tank in 6 hours.

    But we know that

    Hence C can alone fill the tank in 6 hours.

  • Question 8/20
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    A principal of Rs. 8000 is lent at 8% per annum on simple interest for 8 years, find the amount after 8 years?
    Solutions

    SI = (PRT)/100

    Hence, SI = (8000×8×8)/100 = Rs 5120

    Amount = Principal + Interest

    Amount = 8000 + 5120 = Rs. 13120

  • Question 9/20
    1 / -0

    An amount was invested at a simple rate of interest p.a. for 5 years. It would have fetched Rs. 300 more had it been invested at 2% higher rate. What was the amount invested?
    Solutions

    Difference in the simple interest in 5 years = 2×5 = 10%

    Given, 10% of the Amount = Rs 300

    Hence, the amount = 300×10 = Rs 3000

  • Question 10/20
    1 / -0

    Directions For Questions

    Direction: The following table represents the turnover of six different firms during a period of six months (in Crores). Study the table carefully and answer the questions that follow.

    ...view full instructions


    What is the average of turnover of company Q in May, R in July, T in August and U in June (in crores)?

    Solutions

    Turnover of company Q in May = 48 crores

    Turnover of company R in July = 75 crores

    Turnover of company T in August = 18 crores

    Turnover of company U in June = 55 crores

    Required average = (48 + 75 + 18 + 55)/4 = 49 crores

  • Question 11/20
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    Directions For Questions

    Direction: The following table represents the turnover of six different firms during a period of six months (in Crores). Study the table carefully and answer the questions that follow.

    ...view full instructions


    By what percent approximately is the turnover of company P in June less than that by company S in the same month?
    Solutions

    Turnover of company P in June = 48 crores

    Turnover of company S in June = 70 crores

    Required percentage = [(70 - 48)/70] × 100 = 31.43%

  • Question 12/20
    1 / -0

    Directions For Questions

    Direction: The following table represents the turnover of six different firms during a period of six months (in Crores). Study the table carefully and answer the questions that follow.

    ...view full instructions


    What is the difference between the turnover of company Q and U together in September and company R and T together in April (in crores)?
    Solutions

    Turnover of company Q and U together in September = 92 + 32 = 124 crores

    Turnover of company R and T together in April = 50 + 28 = 78 crores

    Required difference = 124 – 78 = 46 crores

  • Question 13/20
    1 / -0

    Directions For Questions

    Direction: The following table represents the turnover of six different firms during a period of six months (in Crores). Study the table carefully and answer the questions that follow.

    ...view full instructions


    In which month was the total turnover of all the company’s maximum?
    Solutions

    Total turnover of all the companies in April = 35 + 38 + 50 + 36 + 28 + 40 = 227 crores

    Total turnover of all the companies in May = 45 + 48 + 65 + 58 + 30 + 37 = 283 crores

    Total turnover of all the companies in June = 48 + 42 + 46 + 70 + 82 + 55 = 343 crores

    Total turnover of all the companies in July = 78 + 58 + 75 + 85 + 65 + 76 = 437 crores

    Total turnover of all the companies in August = 23 + 27 + 43 + 25 + 18 + 32 = 168 crores

    Total turnover of all the companies in September = 60 + 92 + 28 + 81 + 53 + 32 = 346 crores

    Clearly, the maximum turnover is in the month of July.

  • Question 14/20
    1 / -0

    If tan8θ-cot2θ=0, where 0 < 80 <  , then what is the value of tan 5θ?
    Solutions

    tan8θ=cot2θ

    cot(900−8θ)=cot2θ

    900−8θ=2θ

    900=10θ

    θ=90

    tan5θ=tan(5×90)

    =tan450=1

  • Question 15/20
    1 / -0

    What is cosec (75o + θ) – sec (15o – θ) – tan (55o + θ) + cot (35o - θ) equal to ?
    Solutions

    cosec(750+θ)=cosec[900−(150−θ)]

    =sec(150−θ)

    and cot(350−θ)=cot[900−(550−θ)]

    =tan(550+θ)

    Now cosec(750+θ)−sec(150−θ)−tan(550+θ)+cot(350−θ)

    =sec(150−θ)−sec(150−θ)−tan(550+θ)+tan(550+θ)=0

  • Question 16/20
    1 / -0

    A circular way of 2m wide around a circular well of diameter of 3 m is to be graved by cement to a depth of 20 cm. What quantity of cement (in cubic meter) are required for graving?
    Solutions

    Area of the circular way = 22/7 (3.52-1.52) = 31.4 m2


     
                                   = 31.4 x 20/100 = 6.28 m3

  • Question 17/20
    1 / -0

    Consider the following statements:
    I.
    II.
    Which of the above statements is/are true?
    Solutions

    When then,

    When then,
  • Question 18/20
    1 / -0

    How many pairs (A, B) are possible in the number 479865AB if the number is divisible by 9 and it is given that the last digit of the number is odd?
    Solutions
    If the number is divisible by 9 the sum of all its digit is divisible by 9
    4+7+9+8+6+5+A+B = 39 + A + B is divisible by 9
    Possible values of B are 1,3,5,7,9 as it is given that last digit is odd
    For B= 1, A=5
    For B = 3, A= 3
    For B= 5, A = 1
    For B = 7, A = 8
    For B = 9, A= 6
  • Question 19/20
    1 / -0

    A lawn 30 m long and 16 m wide is surrounded by a path 2 m wide. What is the area of the path?
    Solutions
    Given, Length of the lawn
    Breadth of the lawn
    Path
    Area of the lawn

    Length of lawn including the path
    Breadth of the lawn including the path
    Area of the lawn including the path
    Therefore, area of the path
    Hence, required area is .
  • Question 20/20
    1 / -0

    If and  then the value of is:
    Solutions



    squaring both sides



    squaring both sides


    adding (1) and (2)


    putting in given options, we get
    A. = 4
    B. = 2
    C. =0.5
    D. =1
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