Today's maths comes to you courtesy of Wembley Master Chef, 44 Harrow Rd, HA9 6PG.
This Pizza Deal poster appears in the window.
That's good value, isn't it?
Well let's check...
First let's scale that down to the cost of one pizza, not two.
Diameter
Price
7 inch
£3.75
9 inch
£4.95
12 inch
£6.95
15 inch
£8.45
We can try to find the best value pizza by calculating price per inch.
Diameter
Price
p per inch
7 inch
£3.75
54p
9 inch
£4.95
55p
12 inch
£6.95
58p
15 inch
£8.45
56p
This suggests the 7 inch pizza is the best value at 54p per inch.
But they're all remarkably close, each just over 50p per inch.
It almost looks like this is how they determined the prices.
But pizzas aren't linear, it's the area that increases.
Please ignore everything in the previous table, it's mathematical rubbish.
We could try to estimate the area by counting the number of pepperoni slices on each pizza.
Diameter
Price
no of slices
p per slice
7 inch
£3.75
12
31p
9 inch
£4.95
26
19p
12 inch
£6.95
32
22p
15 inch
£8.45
35
24p
This suggests the 9 inch pizza is the best value at 19p per slice of pepperoni.
The 15 inch pizza might look more packed but its slices are 22p each.
However this is also mathematical rubbish because you can't just go by photos.
In particular the 12 inch and 15 inch pizzas are shown pretty much the same size, and they're not.
My suspicion is that these pizza images aren't real, merely AI conjuring.
So we can't use fictional pepperoni slices to calculate best value either.
What we should be doing is calculating the area of each pizza in square inches.
It's good old A=πr².
Diameter
Price
Area
p per sq in
7 inch
£3.75
38 sq in
10p
9 inch
£4.95
64 sq in
8p
12 inch
£6.95
113 sq in
6p
15 inch
£8.45
177 sq in
5p
That's more like it.
The 7 inch pizza is the worst value at 10p per square inch.
And the 15 inch pizza is the best value at 5p per square inch.
This is because a 15 inch pizza is a lot bigger than it sounds.
Diameter
Area
compared to 7 inch
7 inch
38 sq in
×1
9 inch
64 sq in
×1.7
12 inch
113 sq in
×3
15 inch
177 sq in
×4.7
A 15 inch pizza is almost 5 times the size of a 7 inch.
But at Wembley Master Chef the price is only roughly double.
So if you want best value cheesy pepperoni stodge, go large.
I also checked the cost of buying these pizzas online. Ouch.
Diameter
Shop deal
Online order
7 inch
£3.75
unavailable
9 inch
£4.95
£8.90
12 inch
£6.95
£11.90
15 inch
£8.45
£14.90
The last column is even if you order online and collect it yourself.
In each case you're paying 75% extra for the privilege of ordering online.
So at the end of all that, two conclusions.
1) Larger pizzas are much better value.
2) Don't order online.
