A percentage question

Illiteracy with percentages in the media is one of my pet peeves. They love big numbers so if a figure increased by a factor of 30 they will say it increased by 3000% which is wrong, the correct number is 2900%. IMHO percentages should only be used with small numbers, up to, say, 100%. It is better to use the factor for greater numbers.

I also love it when they say things like “sales decreased by 250%” (what?) We all know reporters are illiterate and don’t have a clue of what they are talking about but this is a bit much.

But to get to the question at hand. There is no doubt or ambiguity. If I have 4 people in the house and one of them gives birth, the population has increased by 25%. If a house has 5 people an one dies, the population has decreased by 20%. I cannot understand the doubt.
the other question: if a store offers a 10% discount a $100 item sells for $90 plus 10% tax= $99
If they offer to pay the tax, I pay $100

I hate mail-in rebates for many reasons but one of them is that it is a really stupid way of wasting money that goes to third parties for no good reason. If a $100 item has a $30 mail-in rebate, I still pay tax on those $30 even though the actual price paid is not the full $100 but $70.

In general I am not for legal regulation of commerce but mail-in rebates are so close to being a scam that I would regulate them closely. How about a law that said something like: “If a mail-in rebate is offered, the vendor is obligated to advance the rebate on the spot and is authorised to subrogate and collect from the manufacturer who offered the rebate” That way the hassle of collecting the rebate falls on the store.

OOps, sorry, didn’t mean to hijacj the thread…