Game Show Stop or Go

You are a contestant on a game show and have accumulated $1000. For the final question you may either stop and take the $1000 home, or play the final question. If you answer correctly your winnings rise to $4000; if you answer wrongly you leave with only $250.

Assume you are risk-neutral and want to maximise expected winnings. What is the break-even probability of answering correctly, above which playing is worthwhile? Give the probability as a decimal.