Final answer:
The period of a pendulum is not affected by the mass of the bob; it depends only on the length of the pendulum and gravity. Doubling the mass will not change the period, which will remain at 4.00 seconds.
Step-by-step explanation:
The period of a pendulum is independent of the mass attached to the string and depends only on the length of the string and the acceleration due to gravity.
The formula for the period T of a simple pendulum is T = 2π√(L/g), where L is the length of the string and g is the acceleration due to gravity. As the formula shows, the mass does not appear in the equation, so doubling the mass will have no effect on the period. The period will remain 4.00 seconds.