Equipment required: 1 brain, TI-Nspire CAS
Sam’s Skate Shop—TI-Nspire CAS
A spreadsheet can be a very useful tool to help businesses keep track of their sales and profits. In this task
we will set up a spreadsheet for Sam, who has just opened a shop selling skateboards, protective gear, skate
clothing and skating DVDs.
Item
Cost Price
($)
%
Mark Up
Skateboard
103
65
Jeans
35
110
Hoodie
20
95
Skate Shoes
42
125
DVD
8.5
50
Helmet
17
76.4
Selling
Price
1 Open a new spreadsheet screen and enter the
details above.
(The CAS screen is not big enough to show all of
this at once so the table is provided.)
Due to the way the TI-Nspire CAS spreadsheet is
set up we will need to abbreviate these headings.
So, at the very top of each column the following
is what should be written:
Profit
Volume
Sold
Volume
Profit
2 To calculate the selling price we will enter a
formula in the shaded cell directly below
the heading sp. The formula required is
‘=cp×(1+(mu÷100))’. Do this now and your
screen should look like this:
item cp mu sp p vs vp
Your screen should look like this:
By referring particularly to the part in brackets,
explain how this formula calculates the selling
price.
3 As we are working with money we would like the
sp column to be in decimal format, showing two
decimal places. To do this we will have to set the
whole of this spreadsheet to two decimal places.
Do this by pressing
> Settings > Settings >
General >
and make Display Digits: Fix 2
and Calculation Mode: Approximate. Then
to
OK and press
. You will then need to press
Copyright © Pearson Australia 2012 (a division of Pearson Australia Group Pty Ltd) ISBN 978 1 4425 4576 2
the Lists & Spreadsheet icon and then
return to your spreadsheet.
>
to
4 Now enter a formula for column E that will
calculate the dollar profit on each item. Make
sure your formula begins with the ‘=’ sign. Do not
work out the profits and enter them manually, as
we will be relying on the use of formulas later on.
As a way of checking your formula, the profit on
a skateboard is $66.95.
find a minimum number of each item that Sam
must sell to make the minimum profit.
8 Sam sells out of DVDs and will not receive a new
order until next week. How many extra skateboards
would he need to sell to make up for the loss of
DVD profits, assuming he sells the same number
of the other items as in Question 5?
9 Sam believes that the mark up on his jeans and
skate shoes is too high, and that he would sell
more at 30% less mark up. Write down the selling
price, the profit, the volume sold and the volume
profit for the jeans and skate shoes from the
original spreadsheet in Question 5 before using
the spreadsheet to answer the following questions.
(a) Find the new selling prices of the jeans and
skate shoes after lowering their mark up by 30%.
(b) How many extra pairs of jeans and shoes will
Sam have to sell at this price to make the
same volume profit as before?
Taking it further
10 Insert some extra columns and a formula into
5 In one fairly typical week, Sam sold 9 skateboards,
27 pairs of jeans, 42 hoodies, 38 pairs of skate
shoes, 86 DVDs and 15 helmets. Enter this
information into your spreadsheet under the
‘Volume sold’ heading. To calculate the profit
made on the volume of each item sold, enter a
formula for column G that will multiply the profit
made on one item by the volume of that item sold.
If you have entered the formula correctly, the
Volume Profit for skateboards should be $602.55.
6 Find Sam’s total profit on all the items sold for
the week. In cell H1 enter ‘=sum(g1:g6)’. The
symbol ‘:’ can be found in the catalog of symbols,
press
> . (We put the formula in this cell
because all of column G is set up with a different
rule.)
your spreadsheet so that you are able to enter the
number of items in stock at the beginning of the
week, and calculate the number left after the
‘Volume Sold’ data is entered.
11 Insert a ‘Discount %’ column and a ‘Sale Price’
column after the ‘Selling Price’ column. Enter a
number of common discounts (such as 10% or
25%) into the ‘Discount %’ column. Enter and fill
down a formula that will calculate the sale price
for you.
(a) If Sam has a ‘20% off everything’ sale,
calculate a minimum combination of items
that need to be sold to obtain his minimum
profit of $4300.
(b) Explain why a 20% discount on the selling
price of an item is not the same as 20% less
mark up on the item.
Answer the following questions by changing
the numbers on your spreadsheet and noting
the effects.
7 Sam has found that he must make a profit of at
least $4300 a week in order to pay the rent on his
shop, his electricity, water and phone bills and to
pay Will, his casual employee who works on
weekends. By changing the number in the
‘Volume Sold’ column (but keeping them in
roughly the same proportion as in Question 5),
Copyright © Pearson Australia 2012 (a division of Pearson Australia Group Pty Ltd) ISBN 978 1 4425 4576 2