Answer:
The 90th percentile of the distribution is 6.512 ml.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the z-score of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Mean of 6 milliliters (ml) and a standard deviation of 0.4 ml.
This means that 
Find the dye amount that represents the 90th percentile (i.e. 90%) of the distribution.
This is X when Z has a p-value of 0.9, so X when Z = 1.28. Then




The 90th percentile of the distribution is 6.512 ml.
No it's longer because 1.29 is bigger
The answer is (rounded to the nearest tenth) about 5.7 and since neither 18 or 2 have a perfect square, so this is irrational.