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Kenzo is driving his car along a road while his friend records the velocity of the car, $v(t)$, in km/h every minute over a 5-minute period - HSC - SSCE Mathematics Advanced - Question 20 - 2020 - Paper 1

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Kenzo is driving his car along a road while his friend records the velocity of the car, $v(t)$, in km/h every minute over a 5-minute period. The table gives the velo... show full transcript

Worked Solution & Example Answer:Kenzo is driving his car along a road while his friend records the velocity of the car, $v(t)$, in km/h every minute over a 5-minute period - HSC - SSCE Mathematics Advanced - Question 20 - 2020 - Paper 1

Step 1

Use the trapezoidal rule

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Answer

To find the approximate distance travelled by the car, we will apply the trapezoidal rule. According to this rule, the integral can be approximated as:

abf(x)dx(ba)2(f(a)+f(b))+i=1n1f(xi).\int_{a}^{b} f(x) \, dx \approx \frac{(b-a)}{2} \left( f(a) + f(b) \right) + \sum_{i=1}^{n-1} f(x_i).

In our case:

  • The time interval [0,5/60][0, 5/60] (which is 5 minutes).
  • The velocities at given intervals are:
    • v(0)=60v(0) = 60 km/h,
    • v(1/60)=55v(1/60) = 55 km/h,
    • v(2/60)=65v(2/60) = 65 km/h,
    • v(3/60)=68v(3/60) = 68 km/h,
    • v(4/60)=70v(4/60) = 70 km/h,
    • v(5/60)=67v(5/60) = 67 km/h.

Next, we can calculate the distances using these values.

Step 2

Calculate the approximate distance

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Answer

Using the trapezoidal rule, we calculate:

Approximate distance=5/6002(v(0)+v(5/60))+i=15/60 at the intervalsv(i)×(1/60)\nTotal=5/602[60+67+2(55+65+68+70)]=52(60)[60+67+2(55+65+68+70)].\text{Approximate distance} = \frac{5/60 - 0}{2} \left( v(0) + v(5/60) \right) + \sum_{i=1}^{5/60 \text{ at the intervals}} v(i) \times (1/60) \n\text{Total} = \frac{5/60}{2} \left[60 + 67 + 2(55 + 65 + 68 + 70)\right] = \frac{5}{2(60)} \left[60 + 67 + 2(55 + 65 + 68 + 70)\right].

Calculating the sum gives:

5120[60+67+2(55+65+68+70)]=6431205.4km.\frac{5}{120}[60 + 67 + 2(55 + 65 + 68 + 70)] = \frac{643}{120} \approx 5.4 \, \text{km}.

Thus, the approximate distance covered by the car is 5.4 km.

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