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A plane needs to travel to a destination that is on a bearing of 063° - HSC - SSCE Mathematics Extension 1 - Question 14 - 2021 - Paper 1

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A plane needs to travel to a destination that is on a bearing of 063°. The engine is set to fly at a constant 175 km/h. However, there is a wind from the south with ... show full transcript

Worked Solution & Example Answer:A plane needs to travel to a destination that is on a bearing of 063° - HSC - SSCE Mathematics Extension 1 - Question 14 - 2021 - Paper 1

Step 1

a) On what constant bearing, to the nearest degree, should the direction of the plane be set in order to reach the destination?

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Answer

To find the required bearing of the plane, we can create a triangle involving the velocity of the plane, the wind velocity, and the resultant velocity toward the destination. Let the angle C be the angle of the plane's heading, and angle A be the bearing of the destination, which is 063°.

Using the sine rule: 175sin(A)=42sin(C)\frac{175}{\sin(A)} = \frac{42}{\sin(C)} Substituting values: 175sin(63°)=42sin(C)\frac{175}{\sin(63°)} = \frac{42}{\sin(C)} Calculating:

o We find (C = \arcsin(\frac{42 \cdot \sin(63°)}{175}))

o This yields a bearing of approximately 058°. Therefore, the required bearing, to the nearest degree, is 058°.

Step 2

b) Use the fact that $\frac{C}{P( C-P )} + \frac{1}{P} = \frac{1}{C-P}$ to show that the carrying capacity is approximately 1,130,000.

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Answer

Let P0=150,000P_0 = 150,000, then P=P0P = P_0 when t=20t = 20, with CC being the carrying capacity. Given that the population in the year 2000 was 600,000:

Substituting into the equation: P(t)=P0e(rt)P(t)=P_0 e^{(r*t)} Substituting values: 600,000=150,000e(r20)600,000 = 150,000 e^{(r*20)} Finding rr:     ln(4)r20    rln(4)20\implies \ln(4) \sim r*20 \implies r \sim \frac{\ln(4)}{20} Now substituting back into the logistic equation, we find: Substituting back leads to: C150,000+1600,000=1C600,000\n\frac{C}{150,000} + \frac{1}{600,000} = \frac{1}{C - 600,000}\nAfter some algebra, we find C1,130,000.C \approx 1,130,000.

Step 3

c) For vector $\mathbf{y}$, show that $\mathbf{y} \cdot \mathbf{v} = |\mathbf{v}|^2$.

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Answer

Let y=v2\mathbf{y} = |\mathbf{v}|^2 where v=(x y z)\mathbf{v} = \begin{pmatrix} x \ y \ z \end{pmatrix}. Thus, yv=(x y z)(x y z)=x2+y2+z2=v2\mathbf{y} \cdot \mathbf{v} = \begin{pmatrix} x \ y \ z \end{pmatrix} \cdot \begin{pmatrix} x \ y \ z \end{pmatrix} = x^2 + y^2 + z^2 = |\mathbf{v}|^2

Step 4

d) Find the sample size required.

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Answer

To determine the required sample size nn to ensure that p^\hat{p} does not exceed 0.0250.025, we utilize the formula: n=(zα/220.5(10.5)(0.025)2)n = \left( \frac{z_{\alpha/2}^2 \cdot 0.5(1-0.5)}{(0.025)^2} \right) Setting zα/2z_{\alpha/2} as approximately 1.96. This calculates to: n=(1.9620.50.50.000625)=1536n = \left( \frac{1.96^2 \cdot 0.5 \cdot 0.5}{0.000625} \right) = 1536 Rounding gives a sample size of approximately 1600.

Step 5

e) Find the gradient of the tangent to $f(x) = xg^{\prime}(x)$ at the point where $x = 3.$

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Answer

First, compute g(x)g'(x): g(x)=3x2+4g'(x) = 3x^2 + 4 Now, evaluate at x=3x = 3: g(3)=3(32)+4=27+4=31g'(3) = 3(3^2) + 4 = 27 + 4 = 31 Thus, f(x)=g(x)+xg(x)f'(x) = g'(x) + xg^{\prime \prime}(x) Finding f(3)f'(3) gives: f(3)=31+3g(3)f'(3) = 31 + 3g^{\prime \prime}(3) This evaluates to the required gradient.

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