mean score of 80 and a standard deviation of 5. Percentage of students that scored between 70 and 90?

Question

mean score of 80 and a standard deviation of 5. Percentage of students that scored between 80 and 90? plzzzzzz helppppp will failllll if I do this wrong. Help!!!!!!!!!!!!!!!!!!!!!!!!!

Answer 1

empirical rule is 68-95-99 or 68-95-99.7

where 68% fall within 1 standard deviation from the mean

95% fall within 2 standard deviations from the mean

from 70 to 90 with mean 80 is 2 standard deviations from the mean if standard deviation = 5 so, 95% fall between 70 to 90

then you ask what percent between 80 and 90?

that's half of 95% or 47.5%

or you could use z tables, or an on line z calculator, or a scientific calculator with statistics functions.