Does the data fit the claim?, step by step

A packet says 1 seed in 5 will fail.

The question

A packet says 1 seed in 5 fails. Of 200 planted, 37 failed. Does that fit the claim?

Work out what the claim predicts, then compare

expected=n ÷ k
1 in 5 of 200 is 40, and the result was 37
It fits the claim
  1. A packet says 1 seed in 5 fails. Of 200 planted, 37 failed. Before judging the result, work out what the claim says to expect — a claim of "1 in k" over n tries predicts n ÷ k.
  2. 1 in 5 of 200 is 40, and the result was 37.
  3. A handful either side of the expected count is what a claim like this looks like when it is true — no result lands exactly on it.

How it works.

  1. 01

    A packet says 1 seed in 5 fails. Of 200 planted, 37 failed. Before judging the result, work out what the claim says to expect — a claim of "1 in k" over n tries predicts n ÷ k.

  2. 02

    1 in 5 of 200 is 40, and the result was 37.

  3. 03

    A handful either side of the expected count is what a claim like this looks like when it is true — no result lands exactly on it.