Which value is not equivalent to the other's​

Mary had at least an 80% on her test write an inequality to represent this situation

What values of c and d make the equation true?

The lengths of nails produced in a factory are normally distributed with a mean of 4.91 centimeters and a standard deviation of 0.05 centimeters. find the two lengths that separate the top 4% and the bottom 4%. these lengths could serve as limits used to identify which nails should be rejected. round your answer to the nearest hundredth, if necessary.