← The Green

The Commons Year · ages 15-18

Last Year on the Green · March: The Extended Warranty

The idea: what a cover is worth is the chance of the loss times its size; insure what you could not afford to lose, and read what you already have.

Read it

Who is in this book

Every recurring character has a short tune, so you can tell who is on stage before a word is said. The tunes play only when you tap, and the Reading Access sound switch turns them off.

The Honest Page

Which parts of this story are true, stretched or made up?

True

  • The expected value of an uncertain outcome is the average of its possible values, each weighted by how likely it is. It is also what you would get on average if the same chance were repeated many times. Source
  • Extended warranties often cost 20% to 30% of an item's price. Consumer groups say they are usually in the seller's interest more than the buyer's, and that buyers often overestimate how likely a fault is. Source
  • In the United Kingdom, the Consumer Rights Act 2015 says goods must be of satisfactory quality, fit for purpose and as described, whatever extra cover you buy. Source
  • In the case, £39 is about 22% of £180; one chance in twenty of a £60 repair is worth about £3; twenty customers paying £39 pay £780, and after one £60 repair £720 is left.

Stretched

  • In the case, the leaflet prints its own claim rate, one customer in twenty. What we simplified: Real leaflets rarely say how often people claim, which makes the sum harder to do. Where the number is missing, it is worth asking for it, and worth asking what is already covered by the maker's guarantee and the law.

Made up

  • The electronics shop, Mr Obi, the leaflet and its numbers, Tara's headphones and her mum's washing machine are made up. The idea of expected value is real.

Tara’s sentence

The case stops where Tara speaks. Write the sentence you would have said. It stays on this device.

Ring the hammer for someone

Pick this book for someone younger. The link carries only the book, and it will wait for them on the Green.

Across the Table → For the grown-up: the story in three lines, one question to ask, and one thing to do together.