A geometric sequence is given by the recursive rule a1=23, an=3an−1. Give an explicit rule for the nth term of the sequence b1, b2, b3, … , given that b1=a1, b2=a3, b3=a5, ….

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?