IB Maths AI SL Topic 5: Calculus 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 1Medium6 marks

A model for the water level in a test tank is

h(t)=0.2t3−1.14t2+1.566t+42,h(t)=0.2t^3-1.14t^2+1.566t+42,

where hh is the water level in centimetres and tt is the time in hours after the start of a test. The model is valid for 0≤t≤40\leq t\leq4

(a)

Show that

dhdt=0.6t2−2.28t+1.566.\frac{dh}{dt}=0.6t^2-2.28t+1.566.
[2]
(b)

Hence determine the intervals in the model domain for which dhdt>0\frac{dh}{dt}>0 and dhdt<0\frac{dh}{dt}<0 State when the water level is increasing and when it is decreasing. Give boundary times to 2 decimal places.

[4]

Question 2

Paper 1Medium6 marks

A manufacturer models its profit, PP in thousands of dollars, when producing xx thousand units, by

P(x)=x33000−0.0204x2+0.27x+20,0≤x≤45.P(x)=\frac{x^3}{3000}-0.0204x^2+0.27x+20,\qquad 0\leq x\leq45.

The model is shown in Figure 1.

0510152025303540451818.51919.52020.52121.522x (thousand units)P(x) (thousand dollars)
(a)

Using a GDC, determine the values of xx at which the gradient of the curve is zero. Give your answers to 1 decimal place.

[2]
(b)

Hence, find the coordinates of both stationary points and state whether each is a local maximum or a local minimum. Give the profit coordinates to 2 decimal places.

[2]
(c)

The owner claims that the local maximum gives the greatest profit in the model’s domain. Use Figure 1 to decide whether this claim is correct. Justify your answer.

[2]

Question 3

Paper 1Medium6 marks

A surveyor estimates the area of an irregular lake inlet. A straight survey line of length 220 m220\text{ m} is laid along one edge of the inlet. At equally spaced stations, the perpendicular distance from the line to the opposite shoreline is measured. The width increases continuously between consecutive stations.

Distance along survey line (m)055110165220
Width (m)015284255
(a)

Use the trapezoidal rule to estimate the area of the inlet. Give your answer to the nearest 10 m210\text{ m}^2

[3]
(b)

Use rectangular strips to find lower and upper estimates for the area. Hence state bounds for the true area and whether your estimate in part (a) is consistent with these bounds.

[3]

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