John and his friend Robert are going to start college next y

John and his friend Robert are going to start college next year and are planning to choose the same major. Let the random variable X denote the percentage of financial aid that John receives as scholarship, and let the random variable Y denote the percentage of financial aid that Robert receives from the same school. The joint probability mass function of X and Y is given in the following table. What is the covariance between John and Robert for getting scholarship? -0.02 0.23 -0.23 0.02

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