Normal Distribution and z-scores. mean: the average obtained by dividing the sum of the data by the number of data in the set. Given a set of data, {x 1, x 2, x 3, ..., x n }, you can find the mean, , using the following formula: standard deviation: the extent to which data differs from the mean.
Quick Answer. Kool-Aid hair dye hair dye can last for eight to 12 weeks. The intensity of the color depends on several factors such as the natural hair color, the amount of time the hair is soaked with the dye, the amount of dye used and the dyeing method used. Continue Reading.
RELATED: How to Tell if Your Hair Is Healthy Enough to Dye. Immediately following your treatment, make sure to invest in a dry shampooâin order for the keratin to live up to its promises, you aren't allowed to wash your hair, or tie it back in a ponytail holder for at least 48 hours.