IB Maths AI SL Topic 2: Functions questions

Exam-style questions in the shape of Paper 1 and Paper 2, with full markschemes. Read the markscheme, or type, photograph or draw your answer and get it marked.

Question 1

Paper 1Easy6 marks

The upper edge of an entrance arch is modelled by y=−0.4(x−5)2+10y=-0.4(x-5)^2+10 where xx is the horizontal distance in metres from the left end of the arch and yy is the height in metres. The model is valid for 0≤x≤100\leq x\leq10

Use graphing technology for each part. Give coordinates in metres.

(a)

State the coordinates of the maximum point of the graph.

[2]
(b)

Determine the coordinates of the xx-intercepts of the graph.

[2]
(c)

A horizontal crossbar is placed at a height of 66 metres. Determine the coordinates where it meets the arch. Give your answers to two decimal places.

[2]

Question 2

Paper 2Medium15 marks

A surveyor records the elevations of points on a mountain access route. In Figure 1, xx is the horizontal distance, in metres, from a reference point and yy is the elevation, in metres.

The existing straight road runs from AA to BB A proposed extension runs from BB to CC Point EE is the proposed starting point of a second access track, which is to be parallel to ABAB

The maximum acceptable gradient for a road is 18%18\% where gradient is the rise divided by the horizontal distance, expressed as a percentage.

050100150200250300350400450500700710720730740750760770780790800810x / my / mABCE
(a)

Calculate the gradient of ABAB as a percentage.

[2]
(b)

Show that the equation of ABAB is

y=2371375x+718.4.y=\frac{237}{1375}x+718.4.
[2]
(c)

Hence, find the horizontal distance from AA at which ABAB reaches an elevation of 750750 m. Give your answer to the nearest metre.

[2]
(d)

The second access track passes through EE and is parallel to ABAB

Write its equation first in the form y−y1=m(x−x1)y-y_1=m(x-x_1) then in the form y=mx+cy=mx+c Hence, find its elevation when x=400x=400 m. Give your answer to the nearest 0.10.1 m.

[6]
(e)

Calculate the gradient of BCBC as a percentage and determine whether the proposed extension meets the maximum acceptable gradient.

[3]

Question 3

Paper 1Easy7 marks

A technician records the volume, VV of water in a container as it is filled from a tap.

tt (minutes)0246
VV (litres)2.64.05.57.0
(a)

State one feature of the measurements that supports using a linear model for VV

[1]
(b)

Using the measurements at t=0t=0 and t=6t=6 determine the gradient mm and intercept cc of the linear model V(t)=mt+cV(t)=mt+c Hence write down the model.

[3]
(c)

Use your model to estimate the volume at t=5t=5 minutes, giving your answer to the nearest 0.10.1 litre. State whether this prediction involves extrapolation, giving a reason.

[3]

Question 4

Paper 1Medium14 marks

A horticulture centre monitors the depth of water in a shallow pond during a controlled fill-and-drain test. Let tt be the time, in hours, since the test began, and let hh be the depth of water, in centimetres.

tt0257
hh1.37.610.17.0
(a)

Choose the most suitable model from a linear, quadratic or exponential model for these data. Justify your choice.

[2]
(b)

Using only the observations at t=0t=0 t=2t=2 and t=5t=5 fit a quadratic model of the form h=at2+bt+ch=at^2+bt+c Show that

h=−0.463t2+4.08t+1.30,h=-0.463t^2+4.08t+1.30,

where the coefficients are given to 3 significant figures. Retain unrounded values for later parts.

[3]
(c)

Use your fitted model to estimate the depth at t=7t=7 Compare your estimate with the recorded depth.

[2]
(d)

Use your fitted model to estimate the time at which the depth is 88 cm on the falling part of the curve. Give your answer to the nearest 0.010.01 hour.

[3]
(e)

State a reasonable domain for using this model, based on the observations. Use the model to estimate the depth at t=10t=10 and comment on whether this prediction is reasonable.

[4]

Question 5

Paper 1Medium14 marks

An engineer records the water height, hh cm, in a reservoir while a pump fills it. The pump remains on throughout a planned 8-minute run, and there is no outlet. The measurements shown in Figure 1 were taken during the first 5 minutes. Heights are recorded to the nearest 0.10.1 cm.

012345678051015202530t (minutes)h (cm)(0, 3.8)(1, 10.3)(2, 15.6)(3, 20.0)(4, 23.1)(5, 25.0)
(a)

Using the shape of the data in Figure 1, choose a linear or quadratic model for hh in terms of tt Justify your choice.

[2]
(b)

Let h=at2+bt+ch=at^2+bt+c Using the measurements at t=0t=0 t=2t=2 and t=4t=4 show that a fitted model is

h=−0.5375t2+6.975t+3.8.h=-0.5375t^2+6.975t+3.8.
[4]
(c)

Hence, using this model, determine the first time during the 5-minute measurement interval at which the model predicts h=25.0h=25.0 cm. Give your answer to the nearest 0.010.01 minute.

[3]
(d)

At t=3t=3 compare the model’s predicted height with the recorded height. State what this comparison suggests about the model’s fit at that time.

[2]
(e)

Use the fitted model to predict the height after 8 minutes. State whether this prediction should be considered reliable, giving two reasons.

[3]

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