The value of the variable x is 7.2
Geometric mean is a mean or average, defined as the nth root of the product of the n values for the set of numbers.
To determine the value of x, we have to use the geometric mean, we have;
4/x = x/13
cross multiply the values, we get;
x × x = 4 × 13
Multiply the values, we get;
x² = 52
Find the square root of both sides, we get;
√(x²) = √52
Then, we have that;
x = 7.2