Hoping someone can help me here because my teacher never teach this lesson just handing out a lecture only. Even I search, I am still can't understand. Thank you!

1. The following are the Math final grade of the previous Grade 11 at Kings College of the Philippines in Statistics and Probability. Compute the mean, variance and standard deviation. 2. Assuming that the grades are normally distributed, what is the probability that the grades is between 85 and 90? Less than 80? Greater than 90? Sketch the normal curve. 3. Who performs better (based from the mean)? Write your complete solutions and final answers Class 1 90 97 91 94 93 90 91 95 95 95 99 94 90 90 97 97 91 97 88 95 90 92 89 91 92 95 96 93 96 96 92 97 95 96 92 93 91 92 90 91 90 90 89 95 Class 2 90 91 89 94 88 94 90 92 92 94 89 90 97 91 90 91 92 89 93 91 90 88 94 86 93 90 94 92 94 83 91 98 92 92 95 96 93 93 90 92 97 93 92 94 94 95 92 93