What is 7/8 times 4/9 how do know without multiplying

What is the sum of these mixed numbers 2 1/8 + 4 3/8

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.

The parabola opens: y=√x-4 (principal square root) up down right left