A parent commented on the grades of her child, Marky, in Math and ESP. His grades in math is 88 and his grade in ESP is 92. She said that the performance of her child is better in ESP. The mean grade of the class in Math is 85 with a standard deviation of 8, whereas the distribution of the ESP grade has a mean of 89 and a standard deviation of 5.
Show a proof that the mother is correct or incorrect in her assertions.
