3500 students take a college entrance exam. The scores on the exam have an approximately normal distribution with mean u = 57 points and standard deviation o = 12 points. Use the 68-95-99.7 rule to complete the following.
(a) Estimate the percentage of students scoring between 33 and 81 points.
(b) Estimate the percentage of students scoring 57 points or more.
(c) Estimate the percentage of students scoring 81 points or more.
(a) Approximately 1% of the students score between 33 and 81 points.
(Type an integer or a decimal.)

5x + 2 = 12 solve the following equation. then place the correct number in the box provided.

An elevator travels 310 feet in 10 seconds. at that speed, how far can't his elevator travel in 12 seconds?

Aprisoner is trapped in a cell containing three doors. the first door leads to a tunnel that returns him to his cell after two days of travel. the second leads to a tunnel that returns him to his cell after three days of travel. the third door leads immediately to freedom. (a) assuming that the prisoner will always select doors 1, 2 and 3 with probabili- ties 0.5,0.3,0.2 (respectively), what is the expected number of days until he reaches freedom? (b) assuming that the prisoner is always equally likely to choose among those doors that he has not used, what is the expected number of days until he reaches freedom? (in this version, if the prisoner initially tries door 1, for example, then when he returns to the cell, he will now select only from doors 2 and 3.) (c) for parts (a) and (b), find the variance of the number of days until the prisoner reaches freedom. hint for part (b): define ni to be the number of additional days the prisoner spends after initially choosing door i and returning to his cell.