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SL Paper 2

Points A and P lie on opposite banks of a river, such that AP is the shortest distance across the river. Point B represents the centre of a city which is located on the riverbank. PB=215km, AP=65km and AP^B=90°.

The following diagram shows this information.

A boat travels at an average speed of 42km h-1. A bus travels along the straight road between P and B at an average speed of 84km h-1.

Find the travel time, in hours, from A to B given that

There is a point D, which lies on the road from P to B, such that BD=xkm. The boat travels from A to D, and the bus travels from D to B.

An excursion involves renting the boat and the bus. The cost to rent the boat is $200 per hour, and the cost to rent the bus is $150 per hour.

the boat is taken from A to P, and the bus from P to B.

[2]
a.i.

the boat travels directly to B.

[2]
a.ii.

Find an expression, in terms of x for the travel time T, from A to B, passing through D.

[3]
b.i.

Find the value of x so that T is a minimum.

[2]
b.ii.

Write down the minimum value of T.

[1]
b.iii.

Find the new value of x so that the total cost C to travel from A to B via D is a minimum.

[3]
c.i.

Write down the minimum total cost for this journey.

[1]
c.ii.



The following table shows the average body weight, x , and the average weight of the brain, y , of seven species of mammal. Both measured in kilograms (kg).

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The average body weight of grey wolves is 36 kg.

In fact, the average weight of the brain of grey wolves is 0.120 kg.

The average body weight of mice is 0.023 kg.

Find the range of the average body weights for these seven species of mammal.

[2]
a.

For the data from these seven species calculate r , the Pearson’s product–moment correlation coefficient;

[2]
b.i.

For the data from these seven species describe the correlation between the average body weight and the average weight of the brain.

[2]
b.ii.

Write down the equation of the regression line y on x , in the form y = m x + c .

[2]
c.

Use your regression line to estimate the average weight of the brain of grey wolves.

[2]
d.

Find the percentage error in your estimate in part (d).

[2]
e.

State whether it is valid to use the regression line to estimate the average weight of the brain of mice. Give a reason for your answer.

[2]
f.



The marks obtained by nine Mathematical Studies SL students in their projects (x) and their final IB examination scores (y) were recorded. These data were used to determine whether the project mark is a good predictor of the examination score. The results are shown in the table.

The equation of the regression line y on x is y = mx + c.

A tenth student, Jerome, obtained a project mark of 17.

Use your graphic display calculator to write down x ¯ , the mean project mark.

[1]
a.i.

Use your graphic display calculator to write down y ¯ , the mean examination score.

[1]
a.ii.

Use your graphic display calculator to write down r , Pearson’s product–moment correlation coefficient.

[2]
a.iii.

Find the exact value of m and of c for these data.

[2]
b.i.

Show that the point M ( x ¯ , y ¯ ) lies on the regression line y on x.

[2]
b.ii.

Use the regression line y on x to estimate Jerome’s examination score.

[2]
c.i.

Justify whether it is valid to use the regression line y on x to estimate Jerome’s examination score.

[2]
c.ii.

In his final IB examination Jerome scored 65.

Calculate the percentage error in Jerome’s estimated examination score.

[2]
d.



A pan, in which to cook a pizza, is in the shape of a cylinder. The pan has a diameter of 35 cm and a height of 0.5 cm.

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A chef had enough pizza dough to exactly fill the pan. The dough was in the shape of a sphere.

The pizza was cooked in a hot oven. Once taken out of the oven, the pizza was placed in a dining room.

The temperature, P , of the pizza, in degrees Celsius, °C, can be modelled by

P ( t ) = a ( 2.06 ) t + 19 ,   t 0

where a is a constant and t is the time, in minutes, since the pizza was taken out of the oven.

When the pizza was taken out of the oven its temperature was 230 °C.

The pizza can be eaten once its temperature drops to 45 °C.

Calculate the volume of this pan.

[3]
a.

Find the radius of the sphere in cm, correct to one decimal place.

[4]
b.

Find the value of a .

[2]
c.

Find the temperature that the pizza will be 5 minutes after it is taken out of the oven.

[2]
d.

Calculate, to the nearest second, the time since the pizza was taken out of the oven until it can be eaten.

[3]
e.

In the context of this model, state what the value of 19 represents.

[1]
f.



Abdallah owns a plot of land, near the river Nile, in the form of a quadrilateral ABCD.

The lengths of the sides are AB = 40 m, BC = 115 m, CD = 60 m, AD = 84 m and angle B A ^ D = 90 .

This information is shown on the diagram.

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The formula that the ancient Egyptians used to estimate the area of a quadrilateral ABCD is

area = ( AB + CD ) ( AD + BC ) 4 .

Abdallah uses this formula to estimate the area of his plot of land.

Show that BD = 93  m correct to the nearest metre.

[2]
a.

Calculate angle B C ^ D .

[3]
b.

Find the area of ABCD.

[4]
c.

Calculate Abdallah’s estimate for the area.

[2]
d.i.

Find the percentage error in Abdallah’s estimate.

[2]
d.ii.



Olivia’s house consists of four vertical walls and a sloping roof made from two rectangles. The height, CD , from the ground to the base of the roof is 4.5 m.

The base angles of the roof are A B C = 27 and A C B = 26 .

The house is 10 m long and 5 m wide.

The length AC is approximately 2.84 m.

Olivia decides to put solar panels on the roof. The solar panels are fitted to both sides of the roof.

Each panel is 1.6 m long and 0.95 m wide. All the panels must be arranged in uniform rows, with the shorter edge of each panel parallel to AB or AC . Each panel must be at least 0.3 m from the edge of the roof and the top of the roof, AF .

Olivia estimates that the solar panels will cover an area of 29 m2.

Find the length AB , giving your answer to four significant figures.

[5]
a.

Find the total area of the two rectangles that make up the roof.

[3]
b.

Find the maximum number of complete panels that can be fitted to the whole roof.

[3]
c.

Find the percentage error in her estimate.

[3]
d.

Olivia investigates arranging the panels, such that the longer edge of each panel is parallel to AB or AC .

State whether this new arrangement will allow Olivia to fit more solar panels to the roof. Justify your answer.

[2]
e.



A factory packages coconut water in cone-shaped containers with a base radius of 5.2 cm and a height of 13 cm.

The factory designers are currently investigating whether a cone-shaped container can be replaced with a cylinder-shaped container with the same radius and the same total surface area.

Find the volume of one cone-shaped container.

[2]
a.

Find the slant height of the cone-shaped container.

[2]
b.

Show that the total surface area of the cone-shaped container is 314 cm2, correct to three significant figures.

[3]
c.

Find the height, h , of this cylinder-shaped container.

[4]
d.

The factory director wants to increase the volume of coconut water sold per container.

State whether or not they should replace the cone-shaped containers with cylinder‑shaped containers. Justify your conclusion.

[4]
e.



A water container is made in the shape of a cylinder with internal height h cm and internal base radius r cm.

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The water container has no top. The inner surfaces of the container are to be coated with a water-resistant material.

The volume of the water container is 0.5   m 3 .

The water container is designed so that the area to be coated is minimized.

One can of water-resistant material coats a surface area of 2000  c m 2 .

Write down a formula for A , the surface area to be coated.

[2]
a.

Express this volume in  c m 3 .

[1]
b.

Write down, in terms of r and h , an equation for the volume of this water container.

[1]
c.

Show that A = π r 2 + 1 000 000 r .

[2]
d.

Find d A d r .

[3]
e.

Using your answer to part (e), find the value of r which minimizes A .

[3]
f.

Find the value of this minimum area.

[2]
g.

Find the least number of cans of water-resistant material that will coat the area in part (g).

[3]
h.



The Tower of Pisa is well known worldwide for how it leans.

Giovanni visits the Tower and wants to investigate how much it is leaning. He draws a diagram showing a non-right triangle, ABC.

On Giovanni’s diagram the length of AB is 56 m, the length of BC is 37 m, and angle ACB is 60°. AX is the perpendicular height from A to BC.

Giovanni’s tourist guidebook says that the actual horizontal displacement of the Tower, BX, is 3.9 metres.

Use Giovanni’s diagram to show that angle ABC, the angle at which the Tower is leaning relative to the
horizontal, is 85° to the nearest degree.

[5]
a.i.

Use Giovanni's diagram to calculate the length of AX.

[2]
a.ii.

Use Giovanni's diagram to find the length of BX, the horizontal displacement of the Tower.

[2]
a.iii.

Find the percentage error on Giovanni’s diagram.

[2]
b.

Giovanni adds a point D to his diagram, such that BD = 45 m, and another triangle is formed.

Find the angle of elevation of A from D.

[3]
c.



John purchases a new bicycle for 880 US dollars (USD) and pays for it with a Canadian credit card. There is a transaction fee of 4.2 % charged to John by the credit card company to convert this purchase into Canadian dollars (CAD).

The exchange rate is 1 USD = 1.25 CAD.

John insures his bicycle with a US company. The insurance company produces the following table for the bicycle’s value during each year.

The values of the bicycle form a geometric sequence.

During the 1st year John pays 120 USD to insure his bicycle. Each year the amount he pays to insure his bicycle is reduced by 3.50 USD.

Calculate, in CAD, the total amount John pays for the bicycle.

[3]
a.

Find the value of the bicycle during the 5th year. Give your answer to two decimal places.

[3]
b.

Calculate, in years, when the bicycle value will be less than 50 USD.

[2]
c.

Find the total amount John has paid to insure his bicycle for the first 5 years.

[3]
d.

John purchased the bicycle in 2008.

Justify why John should not insure his bicycle in 2019.

[3]
e.



An archaeological site is to be made accessible for viewing by the public. To do this, archaeologists built two straight paths from point A to point B and from point B to point C as shown in the following diagram. The length of path AB is 185 m, the length of path BC is 250 m, and angle A B C is 125°.

The archaeologists plan to build two more straight paths, AD and DC. For the paths to go around the site, angle B A D is to be made equal to 85° and angle B C D is to be made equal to 70° as shown in the following diagram.

Find the distance from A to C.

[3]
a.

Find the size of angle B A C .

[3]
b.i.

Find the size of angle C A D .

[1]
b.ii.

Find the size of angle A C D .

[2]
c.

The length of path AD is 287 m.

Find the area of the region ABCD.

[4]
d.