IB Maths AI HL/Question Bank/1.1 Number and algebra - SL content

IB Maths AI HL 1.1 Number and algebra - SL content Question Bank

HL65 questions10 previewsSyllabus linked

[Maximum number: 1]

Madhu is designing a jogging track for the campus of her school. The following diagram shows an incomplete portion of the track.
Madhu wants to design the track such that the inner edge is a smooth curve from point A to point B , and the other edge is a smooth curve from point C to point D . The distance between points A and B is 50 metres.

To create a smooth curve, Madhu first walks to M , the midpoint of $[\mathrm{AB}]$ .

(a)

Write down the length of $[\mathrm{BM}]$ .

[ 1 ]

[Maximum number: 19]

Give your answers in parts (a), (d)(i), (e) and (f) to the nearest dollar.
Daisy invested 37000 Australian dollars (AUD) in a fixed deposit account with an annual interest rate of 6.4 % compounded quarterly.

(a)

Calculate the value of Daisy's investment after 2 years.

After m months, the amount of money in the fixed deposit account has appreciated to more than 50000 AUD.

[ 3 ]

(b)

Find the minimum value of m, where $m \in \mathbb{N}$ .

Daisy is saving to purchase a new apartment. The price of the apartment is 200000 AUD.
Daisy makes an initial payment of 25 % and takes out a loan to pay the rest.

[ 4 ]

(c)

Write down the amount of the loan.

The loan is for 10 years, compounded monthly, with equal monthly payments of 1700 AUD made by Daisy at the end of each month.

[ 1 ]

(d)

For this loan, find

[ 5 ]

(i)

the amount of interest paid by Daisy.

(ii)

the annual interest rate of the loan.

After 5 years of paying off this loan, Daisy decides to pay the remainder in one final payment.

[ 5 ]

(e)

Find the amount of Daisy's final payment.

[ 3 ]

(f)

Find how much money Daisy saved by making one final payment after 5 years.

[ 3 ]

[Maximum number: 4]

The growth of a particular type of seashell is being studied by Manon. At the end of each month Manon records the increase in the width of a seashell since the end of the previous month.
She models the monthly increase in the width of the seashell by a geometric sequence with common ratio 0.8 . In the first month, the width of the seashell increases by 4 mm .

(a)

Find by how much the width of the seashell will increase during the third month, according to her model.

[ 2 ]

(b)

Find the total increase in the width of the seashell, predicted by Manon's model, during the first year.

Manon's seashell had a width of 25 mm at the beginning of the first month.

[ 2 ]

[Maximum number: 7]

Give answers to this question correct to two decimal places.
Pierre invests 1500 euros (EUR) at the end of each month for 10 years into a savings plan that pays a nominal annual interest rate of 3.6 % compounded monthly.

(a)

Calculate the value of Pierre's savings plan at the end of the 10 years.

At the end of the 10 years, Pierre withdraws 100000 EUR from the savings plan to use as a deposit on a house.

Pierre invests the remainder into another account for 15 years at a nominal annual interest rate of 4.5 % compounded quarterly.

[ 3 ]

(b)

Calculate the amount in Pierre's account at the end of this time.

[ 4 ]

[Maximum number: 2]

A large water reservoir is built in the form of part of an upside-down right pyramid with a horizontal square base of length 80 metres. The point C is the centre of the square base and point V is the vertex of the pyramid.

diagram not to scale

The bottom of the reservoir is a square of length 60 metres that is parallel to the base of the pyramid, such that the depth of the reservoir is 6 metres as shown in the diagram.

The second diagram shows a vertical cross section, MNOPC, of the reservoir.

(a)

By finding an appropriate value, determine whether Joshua is correct.

To avoid water leaking into the ground, the five interior sides of the reservoir have been painted with a watertight material.

[ 2 ]

[Maximum number: 22]

Thai cushions are designed with a triangular cross-section and are made from layers of smaller cushions. These cushions can be modelled as triangular prisms.
This is shown in the diagram.

Thai cushion with 4 layers

Cross-section of Thai cushion with 5 layers

(a)

Write down the number of triangular prisms in the bottom layer of the cushion with

[ 2 ]

(i)

4 layers.

(ii)

5 layers.

Mayumi notices that the number of triangular prisms in the bottom layer of the cushions forms an arithmetic sequence.

[ 2 ]

(b)

(i)

Write down the common difference of this sequence.

[ 3 ]

(ii)

Find an expression for the number of triangular prisms in the bottom layer of a cushion with n layers.

Mayumi wants to extend this design to create a cushion with 9 layers.

[ 3 ]

(c)

(i)

Find the number of triangular prisms in the bottom layer of Mayumi's cushion.

[ 3 ]

(ii)

Calculate the total number of triangular prisms in Mayumi's cushion.

[ 3 ]

(d)

Find an expression for the total number of triangular prisms in a cushion with n layers, giving your answer in its simplest form.

[ 2 ]

(e)

The cross-section of the cushion consists of black triangles and white triangles.

This cushion with 4 layers has a total of 6 white triangles.

This cushion with 5 layers has 4 white triangles in its bottom layer.

Write down the total number of black triangles in a cushion with 4 layers.

The number of black triangles in each layer forms an arithmetic sequence.

[ 1 ]

(f)

Find and simplify an expression for the total number of black triangles in a cushion with n layers.

The total number of white triangles in a cushion with n layers is $\frac{n(n-1)}{2}$ .

[ 2 ]

(g)

Using both the given expression and your answer to part (f), find and simplify an expression for the total number of black and white triangles in a cushion with n layers.

[ 3 ]

[Maximum number: 6]

Kailash manufactures drink containers in the shape of a cuboid. The container has a square top and a square base of length, $l \mathrm{~cm}$ . Its height, $d \mathrm{~cm}$ , is three times the length of the base.

(a)

Write down an expression for d in terms of l.

The container can hold $375 \mathrm{~cm}^{3}$ of drink.

[ 1 ]

(b)

Find the value of l and d.

[ 3 ]

(c)

Find an expression for the height, h, of the container in terms of r.

Let the total external surface area be $A \mathrm{~cm}^{2}$ .

[ 2 ]

[Maximum number: 13]

The following question explores how sequences, series and Markov chains may be used in modelling the number of customers in a commercial setting.
In a town, there are three stores: Aroma, Bodega and Clover.
Ashley is the manager of Aroma. She gathers data to determine whether there is significant movement of customers between the three stores over the course of one year.
She found that:
- 91 % of Aroma customers stayed with Aroma, 5 % moved to Bodega, and 4 % moved to Clover.
- 95 % of Bodega customers stayed with Bodega, 4 % moved to Aroma, and 1 % moved to Clover.
- 92 % of Clover customers stayed with Clover, 6 % moved to Aroma, and 2 % moved to Bodega.
This information is used to form a transition matrix, T.

(a)

Use Model 1 to find the number of customers Ashley can expect Dusk to have in her 10th week.

Ashley wants to increase the number of customers at Dusk, so she introduces a loyalty scheme after her 5th week. She anticipates that the number of new customers she can expect each week should be 12 % greater than the number of new customers the previous week (Model 2).

[ 2 ]

(b)

Show that the number of customers in Ashley's 6th week, according to Model 2, is 753.6 .

[ 2 ]

(c)

Use Model 2 to find how many customers Ashley should expect in her 10th week.

[ 3 ]

(d)

By comparing the two models, determine the first week in which there would be an expected difference of at least 500 customers.

[ 6 ]

[Maximum number: 16]

Scott purchases food for his dog in large bags and feeds the dog the same amount of dog food each day. The amount of dog food left in the bag at the end of each day can be modelled by an arithmetic sequence.
On a particular day, Scott opened a new bag of dog food and fed his dog. By the end of the third day there were 115.5 cups of dog food remaining in the bag and at the end of the eighth day there were 108 cups of dog food remaining in the bag.

(a)

Find the number of cups of dog food

[ 4 ]

(i)

fed to the dog per day;

(ii)

remaining in the bag at the end of the first day.

[ 4 ]

(b)

Calculate the number of days that Scott can feed his dog with one bag of food.

In 2021, Scott spent $ 625 on dog food. Scott expects that the amount he spends on dog food will increase at an annual rate of 6.4 %.

[ 2 ]

(c)

Determine the amount that Scott expects to spend on dog food in 2025. Round your answer to the nearest dollar.

[ 3 ]

(d)

(i)

Calculate the value of $\sum_{n=1}^{10}\left(625 \times 1.064^{(n-1)}\right)$ .

[ 3 ]

(ii)

Describe what the value in part (d)(i) represents in this context.

[ 3 ]

(e)

Comment on the appropriateness of modelling this scenario with a geometric sequence.

[ 1 ]

[Maximum number: 9]

Imani invests $ 3000 in a bank that pays a nominal annual interest rate of 1.25 % compounded monthly.

(a)

Calculate the amount of money Imani will have in the bank at the end of 6 years. Give your answer correct to two decimal places.

[ 3 ]

(b)

Calculate the number of months it takes until Imani has at least $ 3550 in the bank.

Imani uses the $ 3550 as a partial payment for a used car costing $ 22000. For the remainder she takes out a loan from a bank.

[ 2 ]

(c)

Write down the amount of money that Imani takes out as a loan.

The loan is for 8 years and the nominal annual interest rate is 12.6 % compounded monthly. Imani will pay the loan in fixed monthly instalments at the end of each month.

[ 1 ]

(d)

Calculate the amount, correct to the nearest dollar, that Imani will have to pay the bank each month.

[ 3 ]