When are fractions used in real life

[TeenTimesTwo]

I was asked today by a y6 I'm helping when fractions are used in real life. I struggled to answer it.

Now, I know we often want basic use like 'a third off'.
I also obviously know about percentages, probability and ratios.

But when 'in real life' do you have to add fractions with different starting denominators, or multiply mixed numbers or whatever?

"If you want to buy weed 😂"

There is a restaurant in Chester with an advertising board outside. They have the prices in fractions for some strange reason.

Not really helpful I know but I thought it was a bit odd.

Accountancy all the time:

1. VAT is 20% atm - so, if we look at a gross amount of a transaction and want to know how much the VAT was, its x 1/6; or conversely if we want to know the net before VAT, its x 5/6. When VAT was 15%, we used 3/23rds.
2. when time apportioning bills to the period they relate to - say the client's Professional subscription runs from January, and the year end is March, then we calculate 3/12 relates to this year, and 9/12 to carry forward into the next accounting year! Likewise, if their last electricity bill was £180 on the February 28th, then we calculate x 1/3 as an estimate for the creditor to put in for March
3. as pp have said, percentages come into calculations for tax, gross profit/net profit, discounts....

To name but a few.....obviously there is all the statistics, sampling, etc

Aircraft fuel calculations any use to you?

More fuel means you can go further, but fuel is heavy, so you burn the fuel quicker the more you have. Different speeds burn fuel at different rates. Different heights burn fuel at different rates. Pilots have to take all that into account and do some fairly complex (albeit approximate) calculations when determining how much to fuel up by. Too much is a waste of expensive fuel (it’s highly volatile so just leaving it in isn’t a great option) too little and you could be dead. Don’t know if that’s the kind of maths you are after.

Tell they need to know so that when they are grown up they can explain fractions to their kids like you are doing for them.

I work in pensions. If you start your pension at 65 and have £x and receive 4.67% compound interest on your birthday how much will you be earning by the time you're 68? If you died at 68 your partner would get 70% of the value but your original amount was guaranteed for 5 years from your original retirement age so it would only drop after that. How much would you get in 7 years time?

Statistics and surveys:

The richest tenth of the world's population produce half of all carbon emissions

uk.businessinsider.com/the-richest-tenth-of-the-worlds-population-produce-half-of-all-carbon-emissions-2015-12

Who knows what the future will bring? When I was young Number Theory was a slightly oddball cerebral diversion. It now forms the basis of internet encryption!

"It is better to know it and not need it than to need it and not know it."

I use fractions quite a bit in recipes/ currency conversion. It's also hard to use a calculator to do them so if for any reason they crop up you have to work it out.

The purpose of long division in a world of calculators, phones, Alexas and computers escapes me. I'm not even sure when you'd use it past y6.

How about playing cards? Trying to work out the chances of the card you need/don’t need coming up (especially when all fave cards are worth ten). Pontoon for example - you’re on 17, what’s the chance you’ll go bust?

Or Yahtzee (the dice game). If a combination can go down as two different things (say three off a kind or add all the threes), which is more likely to happen again. Although that attracts a points reward too, so not just fractions going on.

So mainly probability. Although I do lots of cooking and chemistry too - so working out dilution factors and stuff like that is really common.

In medicine! Drug calculations, radiography, RER (resting energy requirements) for patients use formulas involving fractions, there's a basic formula then you have existing and ongoing losses etc to account for. I use fractions a lot in my work (veterinary).

But you need to explain what "science and engineering jobs" means.
So ' if you are working out the right amounts of medicine, or making a new medicine or building a bridge/road/building/new vacuum cleaner/ computer/power station/car/plane etc'

I work part time - I'm looking for a new job and comparing pro rata salaries for roles with different hours. So I currently work 16 hours of a 37.5 hour week pro rata of X per year, how much better off will I be if I get the job I have applied for at 3/5 of y per year ( the answer is over £400 per month so fingers crossed!)

I’m a project manager (construction). I use fractions all the time - in appraising tenders (the criteria for giving someone a job might be say 1/3 cost; 1/3 quality; 1/3 Health and Safety. Or in calculating “pain/gain” on project costs - if a project is delivered before the agreed deadline, then the contractor gets a bigger share of the profit based on target price/if later, they lose more. I working out how much of target cost has been spent, and what efficiencies have been made. What profit has been made! In publically funded works, the basis of if a scene gets funded depends on its cost:benefit ratio (a ratio is essentially a fraction).

Thank you all.

In summary:

Everyone uses basic fractions, ratios and percentages in day to day life.

Harder stuff like adding lots of fractions with different denominators or multiplying mixed fractions is used by lots of people in various jobs, but not in people's home lives.

And some people on MN read the title and not the full post

I think it depends on the industry you want to work in. I appreciate that a lot of people will never use maths in their day to day lives, but I work in tax so use fractions and algebra frequently.

And some people on MN read the title and not the full post
That's me then

DS1 is suggesting cryptography (code breaking), map scaling and nuclear stuff but he's only 15 and not totally reliable

If they fancy a career as a maths teacher 😂

Other stuff seems to be more easy to find a day-to-day use:

Areas of triangles: so you can cut a slice of cake in half fairly

Trig: to see whether the tree you want to cut down is tall enough to fall on your house if you get the angle wrong.

Pythag: getting things through narrow doorways or wide sheets of something into cars (though of course you could just measure the diagonal)

Areas of circles: working out which is better value a large or medium pizza

Converting units: so the Hubble space telescope is made correctly

I have to scale up a recipe for 12 to feed 30 people today. I am planning to calculate the quantity of each item on the fly, as twice as much, plus half as much again. So the 8 chicken breasts will become 20. I'm pretty sure that is using fractions.

If a footballer wants to get better become a professional they will do all sorts of exercises that appear to have nothing to do with kicking a ball. Yet those exercises make them stronger, faster, increased endurance etc etc.

The same is true with jobs that require any sort of numerical thinking. You need to comprehend and be able to use decimals, percentages, fractions etc etc to develop your brain so you are able to cope with more complex jobs in a numerical society. Its not enough to understand a calculator, if you dont understand fractions you wont know what to input into a calculator to do a calculation.

Proportion of time. Particularly useful for surviving long shifts. I was very good at fractions when working 72 hours straight...