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Number Skills

Question 1

[Maximum marks: 5]



The exact answer to a problem is given by \(\alpha = 789.654\).


a) Give \(\alpha\) correct to 3 significant figures.


(b) Solve the following:

(i) Give \(\alpha\) correct to 2 decimal places.

(ii) Using the answer to (b)(i), write \(\alpha\) in the form \(a \times 10^{k}\), where \(1 \leq a < 10\) and \(k \in \mathbb{Z}\).


c) Find the percentage error to 3 decimal places using the answer to (a)(i).

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Question 2

[Maximum mark: 8]



Given that \(p = \frac{8cos(θ)}{3x + 2y} + z\), where \(θ=45°, \ x=6, \ y=9, \ and \ z=4\). Calculate the value of \(p\) in formats given below.


a) Calculate the exact value of \(p\).


b) Write down your answer from part (a) rounded to 3 decimal points.


c) Write down your answer from part (a) in the form \(a * 10^k\), where \(k=2\)

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Question 3

[Maximum mark: 12]



A cuboid has the following dimensions: length = 4.8 cm, height = 9.1 cm, width = 5.8 cm.




a) Calculate the exact volume of the cuboid in cm3.


b) Give the value obtained in part (a) to dm3.


c) Write the answer for part (a) correct to 2 significant figures.


Mark is instructed to paint the cuboid using black and white paint. Black paint is used for the top and bottom (4.8cm x 5.8cm), and white paint is used for the sides. The cost of covering 1cm2 with black paint is 0.15$, and with white paint it is 0.12$.


d) How much will mark have to spend to paint the entire cuboid? Round your answer to 2 decimal points.

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Question 4

[Maximum mark: 6]



The answer found to a given problem is \(w=0.3862901\).



a) State value \(w\) correct to 2 significant figures.


b) Write down the exact value of \(w\) in the form \(a * 10^k\), where \(1 < a < 10\) and state the value of k.


c) Provided the correct answer to the value of \(w\) is 0.427, what is the percentage error (to 2 decimal places) in the answer found?

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Question 5

[Maximum mark: 9]



Given that \(q = \frac{12x^2sin(α)}{5x^2 + 2y}\) where \(α=60°, \ x=3, \ y=9\).


a) Calculate the value of \(q\) in the simplest form of \(\frac{v\sqrt{3}}{w}\), where \(v\) and \(w\) are positive integers.


b) Find the value of \(q\) rounded to 3 significant figures.


c) Write down your answer to part (b) in the form \(a * 10^k\), where \(k=4\)


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Question 6

[Maximum mark: 7]



Consider a cylinder, as shown on the figure below:




a) Find the volume of the cylinder (to 3 significant figures).


Blue paint is being used to paint the entire cylinder, apart from its top.

b) Calculate the area of the cylinder painted in blue to 2 decimal places.


The cost of 1cm2 of the paint is $0.05. Sara would estimate the cost of having painted the cylinder blue to be $20.


c) Using your answer to part (b), what is the percentage error in Sara’s estimate? Round your answer to two decimal places.

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Question 7

[Maximum mark: 5]



Alice is a farmer testing the accuracy of a submetric GPS service.

She knows the area of a rectangular plot of land to be exactly \( 2646 \, \text{m}^2 \).


Alice measures the length and width to be \( 98.4 \, \text{m} \) and \( 26.2 \, \text{m} \), respectively.


a) Answer the following questions:

(i) Find the area of the plot of land using the GPS measurements.

(ii) What is the percentage error in the estimated area? Give your answer accurate to 3 decimal places.


b) Alice needs to build a fence diagonally in that plot of land.

(i) How long will the fence have to be? Round your answer to 5 significant figures.

(ii) Write down your answer to part (b)(i) as \( a \times 10^k \), where \( 1 \leq a < 10 \) and \( k \in \mathbb{Z} \).

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Question 8

[Maximum mark: 9]



The volume of a trapezoidal is given by:

\[ V = \frac{1}{2}(a + b) * h * l\]

Where a = short base, b = long base, h = height, l = length.




Consider a trapezoidal prism in which a = 2.4cm, b = 3.6cm, h = 3.1cm, and l = 8cm.


a) Calculate its volume.


b) Round your answer to the neareast integer.


c) Write down the exact value for the volume in the form \(a * 10^k\), where \(1000 < a < 10000\) and state the value of k.

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Question 9

[Maximum mark: 6]



The formula for the distance between two points is given by:

\[ \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\]

Consider point A with coordinates (3,5), and points B with coordinates (6,1).


a) Find the distance between points A and B.


Now, consider point C with coordinates (2,4), and points D with coordinates (8,9). Alex believes that the distance between points C and D is twice the distance between points A and B.


b) Find out whether Alex was correct.

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Question 10

[Maximum marks: 8]



Frank wants to fit a glass into a rectangular window frame whose length and width are \( 83 \, \text{cm} \) and \( 57 \, \text{cm} \), respectively.


The percentage error for the length and width of the glass are \( 5\% \) and \( 2\% \), respectively, when compared to the window.


a) Find the lower bound for the area of the glass in \( \text{m}^2 \) and give your answer to 3 significant figures.


b) Find the upper bound for the area of the glass in \( \text{m}^2 \) and give your answer to the nearest hundredth.


c) Using the results in parts \( \text{(a)} \) and \( \text{(b)} \), find the percentage error in the area of the glass given correct to 3 decimal places.

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Question 11

[Maximum marks: 5]



Jack is a physicist working at Fermilab who measured the lifetime of a muon to be \(t = 0.00219864 \, \text{ms}\).


a) State the value of \(\text{t}\) to 3 significant figures.


b) Write down the exact value of \(\text{t}\) (in \(\text{ms}\)) in the form \(\text{a} \times 10^{k}\), where \(\text{1} \leq \text{a} < 10\) and \(\text{k} \in \mathbb{Z}\). State \(\text{a}\) accurate to 3 decimal places.


The actual lifetime of a muon is thought to be \(\tau = 2.1969811 \, \text{μs}\).


c) What is the percentage error in Jack's measurement to the nearest thousandth?

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Question 12

[Maximum marks: 6]



Laura is an engineer helping in the design of a torsion balance. In her design, the torsion constant is \(\kappa = 2028\) and the inertia of the system is \(\text{I} = 8281\). Given that they are related to the period by the formula:


\[\tau = 2 \pi \sqrt{\frac{I}{\kappa}} \text{ in } \text{ms}\]


a) Calculate the exact value of \(\tau\) in simplest form of \(\frac{a \pi \sqrt{b}}{c}\), where \(\text{a}\), \(\text{b}\), and \(\text{c}\) are positive integers.


b) Find the value of \(\tau\), in seconds, in the form \(\text{a} \times 10^{k}\), where \(\text{1} \leq \text{a} < 10\) and \(\text{k} \in \mathbb{Z}\). Give the value of \(\text{a}\) to 3 significant figures.


Laura measured the period to be \(\tau = 12.5 \, \text{ms}\).


c) What is the percentage error, given correct to 3 decimal places?

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Question 13

[Maximum marks: 7]



The arc length of a Catenary of equal strength is given by the formula:


\[ s = \ln \left(\tan \left(\frac{\pi + 2 \phi}{4}\right)\right) \]


a) Find the arc length if \(\phi = 60^{\circ}\) correct to 4 significant figures.


b) Write your answer to part (a) in the form \(a \times 10^{k}\), where \(100 \leq a < 1000\) and \(k \in \mathbb{Z}\).


(c) The value of \(\phi\) increased by 5%.

(i) Find the new value of the arc length to 3 decimal places.

(ii) Find the percentage error in \(s\) to 2 decimal places.

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