When two objects of different weights but same size and shape are released from the same height in vacuum, they will both experience the same acceleration due to gravity. This acceleration is independent of the mass or weight of the objects. Therefore, the time taken for both the iron ball and wooden ball to reach the ground will be equal.

Option 1 states that the time taken will be more for the iron ball, which is incorrect. The acceleration due to gravity is the same for both objects, so they will fall at the same rate.

Option 2 states that the time taken will be more for the wooden ball, which is also incorrect. Again, since the acceleration due to gravity is the same for both objects, they will fall at the same rate.

Option 4 states that the time taken will be in the ratio of their weights. This is incorrect because the time taken to reach the ground is determined by the acceleration due to gravity, not the weight of the objects.

Therefore, the correct answer is option 3: the time taken to reach the ground will be equal for both the iron ball and the wooden ball.