Using percentages incorrectly

[pingu393]

Tony2or4 said:

10% of 110 is 11, so you'd only be 99% behind it.

Reminds me of when a salesman admitted that they had recently upped their prices by 10% and told me he would knock 10% off to make a sale. He couldn't understand why the reduced price was less than the original price .

I left him scratching his head and complaining that his calculator must be broken.


(100 + 10%) = 110

10% of 110 = 11

110 - 11 = 99

[Tony2or4]

pingu393 said:

Reminds me of when a salesman admitted that they had recently upped their prices by 10% and told me he would knock 10% off to make a sale. He couldn't understand why the reduced price was less than the original price .

I left him scratching his head and complaining that his calculator must be broken.


(100 + 10%) = 110

10% of 110 = 11

110 - 11 = 99

I well remember that the mathematics behind reversing percentage changes was something that schoolboys, almost by tradition, found hard to grasp.

[djgritt]

My employer requests that all employees strive to make the group 10000% Compliant.

When my department were asked by the Legal & Compliance team if we knew what 10000% was, the answer 'Bad Statistics' wasn't appreciated for some reason.

Seemingly it's 100% Compliance, 100% of the time.

The company is American, which may explain it...

[xRIEx]

RizzoTheRat said:

The mean is 60.7%

The arithmetic mean

[CoolHands]

zcacogp said:

Because they are fuktards who don't know anything about language.

Much the same as people who say "I'm 200% committed to this" (or similar.)

but what if they're twice as committed as you?

[TwigtheWonderkid]

A friend bought an item from a car boot and sold it for twice as much online. Thought he'd made 100% profit. Tried to explain that he charged 100% mark up, but couldn't make 100% profit on any item he'd paid for, as a % of the sale price would always be the cost price. As he'd sold for twice purchase price, then the sale price was 50% profit.

He wasn't having it.

The old problem of percentages varying when added and deducted came to light recently when they did away with motor insurance sex discrimination. They had to equalise rates for men and women with otherwise identical details.

So, for example, a female was paying £1000 and her twin brother was paying £2000 for similar car at the same address. Now they would both pay £1500. But according to the press, women were being ripped off as her premium was rising by 50% whilst his was only falling 25%.

The story was spun to read rip off insurers taking advantage of the new law to increase women's premiums by a bigger % than they would reduce men's. Which was true, but deliberately misleading.

[Some Gump]

amancalledrob said:

My thread has arrived

I work in private medical insurance. No claims discounts are a nightmare - eg member has 50% NCD. Makes claim. NCD goes down to 35%. Member's premium was £100 and now it's £130, member wants to know why their premium appears to have increased 30%. Well, it hasn't. It's gone up 15%.

Try explaining that to a militant 65yo housewife.

Boils my piss. Grinds my gears. All manner of other PH-specific clichés too

I think you should go and learn maths, then you might not get frustrated with it as much.

The premium has increased by 15%.
This is because the discount on £200 has reduced by 15%

If you're trying to explain this by saying "it hasn't, it's only gone up 15%", then it no wonder you struggle

[Tony2or4]

TwigtheWonderkid said:

A friend bought an item from a car boot and sold it for twice as much online. Thought he'd made 100% profit. Tried to explain that he charged 100% mark up, but couldn't make 100% profit on any item he'd paid for, as a % of the sale price would always be the cost price. As he'd sold for twice purchase price, then the sale price was 50% profit.

Are you saying that the profit should be expressed as a percentage of the sale price rather than as a percentage of the cost price?

[TwigtheWonderkid]

Tony2or4 said:

TwigtheWonderkid said:

A friend bought an item from a car boot and sold it for twice as much online. Thought he'd made 100% profit. Tried to explain that he charged 100% mark up, but couldn't make 100% profit on any item he'd paid for, as a % of the sale price would always be the cost price. As he'd sold for twice purchase price, then the sale price was 50% profit.

Are you saying that the profit should be expressed as a percentage of the sale price rather than as a percentage of the cost price?

That would be my understanding. Buy for a pound and sell for £100, 99% is profit. You can never make 100% profit unless you never paid for the item you've sold. Buying at £50 and selling for £100 is 50% profit, on a 100% mark up.

That's the way I've always expressed it anyway. Happy to be educated otherwise.

[Spare tyre]

Tony2or4 said:

10% of 110 is 11, so you'd only be 99% behind it.

Out of 100 I'd give him 1%

[xRIEx]

djgritt said:

My employer requests that all employees strive to make the group 10000% Compliant.

When my department were asked by the Legal & Compliance team if we knew what 10000% was, the answer 'Bad Statistics' wasn't appreciated for some reason.

Seemingly it's 100% Compliance, 100% of the time.

The company is American, which may explain it...

If they tried doing that calculation in Excel, it would prove the answer is still 100%.

[Otispunkmeyer]

xRIEx said:

djgritt said:

My employer requests that all employees strive to make the group 10000% Compliant.

When my department were asked by the Legal & Compliance team if we knew what 10000% was, the answer 'Bad Statistics' wasn't appreciated for some reason.

Seemingly it's 100% Compliance, 100% of the time.

The company is American, which may explain it...

If they tried doing that calculation in Excel, it would prove the answer is still 100%.

thats because in excel, 100% = 1 (1x1 = 1)

I normally treat percentages as values between 0 and 1. Don't know why, just do. Easier to deal with.

[Tony2or4]

TwigtheWonderkid said:

Tony2or4 said:

TwigtheWonderkid said:

A friend bought an item from a car boot and sold it for twice as much online. Thought he'd made 100% profit. Tried to explain that he charged 100% mark up, but couldn't make 100% profit on any item he'd paid for, as a % of the sale price would always be the cost price. As he'd sold for twice purchase price, then the sale price was 50% profit.

Are you saying that the profit should be expressed as a percentage of the sale price rather than as a percentage of the cost price?

That would be my understanding. Buy for a pound and sell for £100, 99% is profit. You can never make 100% profit unless you never paid for the item you've sold. Buying at £50 and selling for £100 is 50% profit, on a 100% mark up.

That's the way I've always expressed it anyway. Happy to be educated otherwise.

I think there's confusion here between two different concepts: the profit expressed as a percentage of the purchase price on the one hand, and what percentage of the selling price consists of profit, on the other hand.

I agree that the latter couldn't be 100% (unless you obtained the item free of charge before selling it), but the former can be 100%.

I think the phrase 'percentage profit' always means the former, rather than the latter.

In the example you quoted originally, if you buy something for £5 then flog it for £10, you have definitely made 100% profit - but only 50% of the selling price consists of profit.

I think you're misinterpreting the statement I sold it for £10, which corresponds to making 100% profit as I sold it for £10 which is 100% profit (meaning the selling price was all profit).

As another example (typical GCSE maths question here!): bloke buys an item for £100 then wants to make 20% profit when he resells it: how much should he resell it for?

The correct and obvious answer is £120.

[Tony2or4]

Otispunkmeyer said:

I normally treat percentages as values between 0 and 1. Don't know why, just do.

You are completely correct to do so: 50% is just another way of saying 0.5.

[Hoofy]

80% of people don't get percentages. The other 25% like to make things up.

[TwigtheWonderkid]

Tony2or4 said:

As another example (typical GCSE maths question here!): bloke buys an item for £100 then wants to make 20% profit when he resells it: how much should he resell it for?

The correct and obvious answer is £120.

Fair point. A more challenging question at GCSE would be : bloke buys an item for £100 then wants 20% of the sale price to be profit when he resells it: how much should he resell it for?

Answer is £125.

[CrutyRammers]

Tony2or4 said:

Otispunkmeyer said:

I normally treat percentages as values between 0 and 1. Don't know why, just do.

You are completely correct to do so: 50% is just another way of saying 0.5.

Indeed. "%" literally means "per 100", and 50 per 100 is indeed 0.5

[Tony2or4]

TwigtheWonderkid said:

A more challenging question at GCSE would be : bloke buys an item for £100 then wants 20% of the sale price to be profit when he resells it: how much should he resell it for?

Answer is £125.

Yep, you're right there, it is more challenging.

It is even more so when you replace the 20% in the question with something less cuddly, like 37%.

(The answer is £158.73)

[Some Gump]

Sorry, profit has always, and should always be expressed as profit margin, not product mark up.
Product mark up only has one use, and that is to make a small number feel larger to people who are trying to pull the wool over their own eyes.

[Tony2or4]

Some Gump said:

Sorry, profit has always, and should always be expressed as profit margin, not product mark up.

What is the formula/definition of profit margin? (I'm not a businessman type.)