Solution:
Let M represent the muffin,
let C represent the coffee.
Given that the probability that a customer will buy a cup of coffee is 0.8, this implies that
A customer buys a muffin 50% of the time when a cup of coffee is bought. This implies that
10% of the time when a cup of coffee is not bought. This implies that
The probability of buying a muffin,when first buying a cup of coffee is evaluated as