From yrs of teaching experience , an english teacher knows that her student's score will be va random variabel between variance = 25 adn mean = 75 how many students in general ,would have to take exam...

From yrs  of teaching experience , an english teacher  knows  that her  student's score  will be va random variabel between variance = 25 adn mean = 75

 how many students in general ,would have to take exam  with a probability of atleast 0.9  , such that the class  average would be within   5 of 75

 dont use CLT , use markov /Chevyshev