Number System


  1. The differences between two numbers is 18. If four times the second numbers is less than three times the first number by 18, then what is the sum of these two numbers?









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    Let first number = p
    and second number = q
    According to the question,
    p - q = 18 ................................(i)
    and 3p - 4q = 18.....................(ii)

    Correct Option: D

    Let first number = p
    and second number = q
    According to the question,
    p - q = 18 ................................(i)
    and 3p - 4q = 18.....................(ii)
    On multiplying Eq .(i) by 3 and subtracting Eq. (ii) from it,we get
    3p - 3q = 54
    3p - 4q = 18
    q = 36
    On putting the value of q in Eq, (i) we get
    p = 18 + q
    ⇒ p = 18 + 36 = 54
    ∴ Required sum = p + q = 54 + 36 = 90


  1. On children's Day, sweets were to be equally distributed amongst 300 children. But on that particular day 50 children remained absent; hence each child got one extra sweet. How many sweet were distributed?









  1. View Hint View Answer Discuss in Forum

    Let total number of sweets distributed on children's day = x
    According to the question,
    x/250 - x/300 = 1

    Correct Option: C

    Let total number of sweets distributed on children's day = x
    According to the question,
    x/250 - x/300 = 1
    ⇒ ( 6x - 5x )/1500 = 1
    ∴ x = 1500
    ∴ Required number of sweets distributed on children's day = 1500



  1. There are two examination halls P and Q. If 10 students shifted P to Q, then the number of students will be equal in both the examination halls. If 20 students shifted from Q to P, then the students of P would be doubled to the students of Q. The number of students would be in P and Q respectively are ?









  1. View Hint View Answer Discuss in Forum

    Let number of students in examination halls P and Q is x and y, respectively

    Then as per the first condition,
    x - 10 = y + 10
    x - y = 20 ..............(i)
    As per the second condition,
    x + 20 = 2( y - 20)
    x - 2y = - 60 ...............(ii)

    Correct Option: D

    Let number of students in examination halls P and Q is x and y, respectively

    Then as per the first condition,
    x - 10 = y + 10
    x - y = 20 ..............(i)
    As per the second condition,
    x + 20 = 2( y - 20)
    x - 2y = - 60 ...............(ii)
    On subtraction Eq. (ii) from Eq. (i), we get
    - y + 2y = 20 + 60
    y = 80
    Putting the value of y Eq. (i) we get,
    x - 80= 20 ⇒ x = 100
    Hence, number of students in examination halls P and Q is 100 and 80, respectively.


  1. A number is greater than the square of 44 but smaller than the square of 45. If one part of the number is the square of 6 and the number is a multiple of 5, then find the number. ?









  1. View Hint View Answer Discuss in Forum

    Let the number be x.
    442 < x < 452
    ⇒ 1936 < x < 2025 ...(i)

    From equation (i), the required number will be any number between 1936 and 2025. Since one part of the number is the square of 6 means one factor is 36.

    ∴ L, C, M of 36 and 5 = 180
    ∴ Number will be multiple of 180 i,e.,
    180 x 11 = 1980 the only value which satisfies the equation (i).

    Correct Option: C

    Let the number be x.
    442 < x < 452
    ⇒ 1936 < x < 2025 ...(i)

    From equation (i), the required number will be any number between 1936 and 2025. Since one part of the number is the square of 6 means one factor is 36.

    ∴ L, C, M of 36 and 5 = 180
    ∴ Number will be multiple of 180 i,e.,
    180 x 11 = 1980 the only value which satisfies the equation (i).



  1. There are 200 question in a 3 hour examination. Among 200 question, 50 are Mathematics, 100 are from GK and 50 are from Sciences. Ram spent twice as much time on each Mathematics question for each other question. How many minute did he spend on Mathematics questions?









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    Method 1
    Let Ram spends p minute on each Mathematics question.
    According to the question.
    50xp + 100 x p/2 + 50 x p/2 = 3 x 60
    Solve the equation.

    Method 2
    Let Ram spends a minute on each sciences and Gk questions.
    According to the question,
    50 x 2a + 150 x a = 3 x 60
    Solve the equation.

    Correct Option: B

    Let Ram spends p minute on each Mathematics question.
    According to the question.
    50 x p + 100 x p/2 + 50 x p/2 = 3 x 60
    p(50+ 50 + 25) = 180
    ⇒ p = 180/125
    ∴ Required time = 50 x 180/125
    ∴ Required time = 2 x 180/5
    ∴ Required time = 2 x 36 = 72 min

    Method 2
    Let Ram spends a minute on each sciences and Gk questions.
    According to the question,
    50 x 2a + 150 x a = 3 x 60
    100a + 150a = 180
    250a = 180
    a = 180/250
    So total time spend on Mathematics question = 2a x 50 question
    So total time spend on Mathematics question = 2 x 50 x 180/250 = 72 minutes