Challenge #1

Idea #150: Findings

As promised, I share my findings on this naive calculation that is to find the cheapest bowl of fruit salad possible. I suppose few people wondered this, and if you get to the bottom of this page, you will know why.

Before we get down to the challenge itself, let's just appreciate how strange fruits really are. They are like edible limbs of plants, that they willingly give to animals so that they can trick them into spreading the seeds to farther reaches. Plants themselves made the evolutionary choice somewhere along the line to be immobile. People found them, and after gathering them for sustenance for few millennia they discovered they could farm them, securing a constant supply. And a fruit tree just keeps giving away food right from the Earth.

Often, when it is mango season here in Brazil, there are so many fruits that they just end up rotting in the ground, because there is not enough people to eat them. More recently in our History, things got really crazy when people did all sorts of selective breeding to the species, and now no one really knows what an apple tasted in the Middle Ages anymore. Fruits got global, you have such a variety in your local market that with a few bucks you can have a feast that in the past was only allowed to a Greek king. Remember this, the next time you take that yummy bite.


Let's head on to the Fruits Challenge!

The real problem is that the challenge was built on the assumption that you could get real good statistics about fruit prices throughout the year. This is, however, not true. It turns out the the few databases found that hold data far back are really badly compromised. You can clearly see that many numbers were simply made up. Well, there are inherent problems of holding information on thousand of farm products, for years and years.

Actual trustworthy data in Brazil is made available on a monthly basis, as part of a government program to make agriculture here more digital friendly, called Prohort (external link in Portuguese). It would take an actual year of collecting this data to actually answer the question properly, and even then it might not be enough as a time period. I found, however, average prices for fruits in all provinces in Brazil, what actually allows for some comparison between regions.

So, there is a spreadsheet, yes!

The first good insight is that you gain much knowledge about fruit prices when you actually tabulate the data in front of you. That is something you don't really realize when you are doing the groceries. A cool thing I did was try to guess how much actual pulp you could get from a fruit, based on rough guesses, because it is no good to compare raw kilograms of fruits, since you don't get the same fruity content out of different ones. Once I did that, it was easy to see that here we can separate fruits in 5 classes according to prices. There should be no problem in doing the same for your regional prices.


Less than $50c (fifty cents of US dollars) per kilogram of fruit:

Watermelon, Coconut, Corn, Passionfruit, Pumpkin, Orange, Melon;

More than $50c and less than $1.00 per kilogram of fruit:

Mango, Bananas, Hawaiian Papaya, Tomatoes, Lemons, Avocados;

More than $1.00 and less than $1.50 per kilogram of fruit:

Mexican Papaya, Pineapple, Pear, Guava, Apple;

More than $1.50 and less than $2.00 per kilogram of fruit:

Most grapes other than Concord grapes;

More than $2.00 per kilogram of fruit:

Concord grapes and Strawberries;

*Prices in the São Paulo (SP) province.


After filtering and sorting out the raw data to select only fruits and not veggies, I extracted the columns from three provinces: Paraná, São Paulo and Rio de Janeiro. It is very simple to find the cheapest bowl of fruit salad actually. Since the rules of the game state that it needs three ingredients at least, and the minimum you can place is 15% of either one, the cheapest bowl of fruit is the one that has 70% of the cheapest ingredient, plus 15% of second cheapest and 15% of the third cheapest. Sounds simple enough right? You would gain absolutely nothing from adding more ingredients, if you are only interesting in finding the cheapest one.

This lead us to the awesome combination corn + green coconut + watermelon, the cheapest fruit salad combination possible, what may to be a hit if someone finds out it cuts down your abdominal fat, but really it is probably the worse tasting thing on Earth. It is probably refreshing though due to the coconut and watermelon. It costs here in the province of São Paulo, only 2 cents of dollar for a 250g bowl. In seriousness, this stuff is so cheap it should be tested just in case it turns out to have good nutritional value, what corn might actually provide.

Then, we tried to actually come up with a combo that was still cheap but better tasting. That lead us to Melon + Cavendish Banana + Mango + Watermelon. The base is still watermelon, the cheapest thing on the market, what should provide all the water this recipe needs. It costs in Paraná, São Paulo and Rio de Janeiro provinces, respectively, 9 cents, 8 cents and 12 cents per bowl. It costs more in Rio de Janeiro because Mango prices there are roughly 30% more expensive than in São Paulo in the time of checking. We call this fruit salad Scrooge's favorite fruit salad.

Finally, if the purpose of all this was to compare prices of fruit salad, it stands to reason to actually raise how much does a regular fruit salad actually costs per bowl. So I went to one of those website where Moms get their recipes from, and tabulated the costs for each ingredient, after a few guesses into actual quantities. It turns out that this particular recipe (that can be checked in the spreadsheet below) costed 28 cents per bowl, average price in all three provinces of study.

So, someone eating Scrooges favorite fruit salad instead of Mom's choice, daily, would save: per month, roughly $5.40; per year $64.60. But it will cost you around $35 to eat this fruit salad per year. It is up to you to decide if that is a lot. All I can say is that it would take you 775 years to buy a brand new car with the savings from the fruit salad, so it really does not seem to be the way to go in terms of domestic saving, unless it is part of an ambitious all-out savings plan. It really only makes sense if you are in this as a trade.

Well this was a funny calculation, I was hoping for more data to work with, but it was OK. Stay sharp, and leave a comment if you'd like!

Calculation Spreadsheet

fruits_challenge_v3.xlsx

BANNER IMAGE CREDITS: ESA/Hubble & NASA, A. Filippenko, R. Jansen

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