Identify the type of study (observational or experimental) described in each situation.

A researcher places 40 houseplants of the same type and size in each of 2 identical soundproof rooms. Each plant receives the same amount of water and light. Classical music is played continuously in one room, and no music is played in the other room. After 2 months, the researcher measures the growth of the plants. _______________________________

A government employee wants to determine how many people travel in each vehicle in his city. He stands at a particular intersection one morning and counts the number of people in each vehicle that pass through the intersection. ________________________________