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NDA I 2024 Mathematics Test - 10
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NDA I 2024 Mathematics Test - 10
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  • Question 1/10
    2.5 / -0.83

    Directions For Questions

    Directions: Read the following information and answer the two items that follow:

    Consider the table

    ...view full instructions


    The two lines of regression are

    Solutions

    Concept:

    The line of regression of y on x is y - y̅ = byx(x - x̅)

    The line of regression of x on y is x - x̅ = bxy(y - y̅)

    Calculation:

    The line of regression of y on x is y - y̅ = byx(x - x̅)

    ⇒ x = 5.548 - 0.129y

    ∴ The two lines of regression are x = 5.548 - 0.129y and y = 6.836 - 0.216x.

  • Question 2/10
    2.5 / -0.83

    Directions For Questions

    Directions: Read the following information and answer the two items that follow:

    Consider the table

    ...view full instructions


    The two regression coefficients byx and bxy respectively are

    Solutions

    Concept:

    Calculation:

    ∴ The regression coefficients byx and bxy are -0.216 and -0.129, respectively.

  • Question 3/10
    2.5 / -0.83

    Solutions

    Concept:

    If y = f(x) then slope of the curve at point a is given by y’ = f’(x = a)

    Calculation:

  • Question 4/10
    2.5 / -0.83

    Solutions

    Concept:

    If y = f(x) then slope of the curve at point a is given by y’ = f’(x = a)

    Calculation:

  • Question 5/10
    2.5 / -0.83

    Solutions

    Concept:

    If y = f(x) then slope of the curve at point a is given by y’ = f’(x = a).

    Calculation:

  • Question 6/10
    2.5 / -0.83

    Read the following information and answer the three items that follow:

    Let f(x) = x2 - x - 6 and g(x) = x + 10

    If h(x) = 5f(x) – xg(x), then what is the derivative of h(x)?

    Solutions

    Concept:

    Formulae

    Calculation:

    Given:

    h(x) = 5f(x) – xg(x), where f(x) = x2 - x - 6 and g(x) = x + 10

    ⇒ h(x) = 5(x2 - x - 6) - x × (x + 10)

    ⇒ h(x) = 5x2 - 5x - 30 – x2 - 10x

    ⇒ h(x) = 4x- 15x - 30

    ⇒ h’(x) = 8x - 15.

    ∴ The derivative of h(x) is 8x - 15.

  • Question 7/10
    2.5 / -0.83

    What is wrong with the following calculation?

    Solutions

    Explanation:

    Referring to the graph for, f(x) =  which is a discontinuous function on [-1, 3] as  it is having an infinite discontinuity at x = 0

    So, the fundamental theorem of calculus does not apply to discontinuous functions.

    ⇒ The value of the integral does not exist.

    ∴ The correct option is (3).

  • Question 8/10
    2.5 / -0.83

    The equation of a plane passing through the line of intersection of the planes x + 2y + 3z = 2 and x - y + z = 3 and at a distance  23from the point (3, 1, -1) is ax + by + cz -17 = 0 The value of a + b + c -17 is

    Solutions

    Given:

    Equation of plane P1 : x + 2y + 3z - 2 = 0

    Equation of plane P2 : x - y + z - 3 = 0 

    The plane through the intersection of above planes is at a distance  from the point (3, 1, -1)

    Concept:

    Equation of plane passing through the intersection of two planes P1 and P2 can be assumed as :

    P1 + λP2 = 0

    Formula:

    The distance of a point (p, q, r) from a plane ax + by + cz = d is given by :

    Calculation:

    Using P1 + λP= 0,

    Equation of plane through the intersection of above planes is -

    (x + 2y + 3z - 2) + λ(x - y + z - 3) = 0      ----      (i)

    ⇒ (1 + λ)x + (2 - λ)y + (3 + λ)z + (-2 - 3λ) = 0

    On solving, λ = -7/2

    Putting λ = -7/2 in equation (i), we get equation of plane as -

    -5x + 11y - z + 17 = 0

    ⇒ 5x - 11y + z - 17 = 0

    ∴ a + b + c - 17 = - 22

  • Question 9/10
    2.5 / -0.83

    Find the area of the region bounded above by y = ex, bounded below by y = x, and bounded on the sides by x =  0 and x = 1.

    Solutions

    Concept:

    The area of the curve between y = f(x) and y = g(x) {where, f(x) ≥ g(x)} between x = a and x = b is

    Calculation:

    The area of the region bounded above by y = ex, bounded below by y = x, and bounded on the sides by x =  0 and x = 1 is given by,

  • Question 10/10
    2.5 / -0.83

    Read the following information and answer the three items that follow:

    Let f(x) = x2 - x - 6 and g(x) = x + 10

    Consider the following statements:

    I. f[g(x)] is a polynomial of degree 2.

    II. g[g(x)] is a polynomial of degree 2.

    Which of the above statements is/are correct?

    Solutions

    Concept:

    If p(x) = a0 + a1x + …… + anxn, where coefficients of x are real and if an ≠ 0 .Then p(x) is a polynomial of degree n.

    Calculation:

    Given: f(x) = x2 - x - 6 and g(x) = x + 10

    Statement I: f[g(x)] is a polynomial of degree 3.

    ⇒ f[g(x)] = f(x + 10) = (x + 10)2 - (x + 10) – 6 = x2 + 100 + 20x - x - 16

    ⇒ f[g(x)] = x2 + 19x + 84

    ⇒ f[g(x)] is a polynomial of degree 2.

    Statement I is correct.

    Statement II: g[g(x)] is a polynomial of degree 2.

    ⇒ g[g(x)] = g(x + 10) = (x + 10) + 10 = x + 20

    ⇒ g[g(x)] is a polynomial of degree 1.

    Statement II is incorrect.

    ∴ Only statement I is correct.

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