Aset of final examinations grades in an introductory statistics course is normally distributed, with a mean of 75 and a standard deviation of 7. complete parts (a) through (d). a.) what is the probability that a student scored below 87 on this exam? b.) what is the probability that a student scored between 68 and 90? c.) the probability is 25% that a student taking the test scores higher than what grade? d.) if the professor grades on a curve (for example, the professor could give a