Please tell me the answer to this question

Given the function f(x) = log base 4(x+8) , find the value of f^-1(2)

Assume that the weights of quarters are normally distributed with a mean of 5.67 g and a standard deviation 0.070 g. a vending machine will only accept coins weighing between 5.48 g and 5.82 g. what percentage of legal quarters will be rejected? round your answer to two decimal places.

Equation for the calculation double 2 and then add 5