1. Explain the most common types of sampling methods. If you needed to survey a city about a new road project, which sampling me
thod would you choose and explain the sample method. 
1 answer:
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Given expression in exponential form : .
We need to convert it into radical form.
<em>Please note: When we convert an exponential to radical form, the top number goes in the exponent of the term and bottom number of the fraction goes in the radical sign to make it nth radical.</em>
We can apply following rule:
.
Therefore,
.
Therefore, correct option is : D. ninth root of a to the fourth power.