What is the maximum value the stock price can take before you are issued a margin call?

Intro: The price of Apple Stock is currently $95.04 and you decide to sell short 600 shares.

Part 1. The initial margin is 60%. How much do you have to contribute at least to the account?

Part 2. If the price rises to $107.23, what is the new percentage margin?

Part 3. If the broker’s maintenance margin is 40%. What is the maximum value the stock price can take before you are issued a margin call?