Say whether each made-up study is a sample survey, an observational study or an experiment…

Say whether each made-up study is a sample survey, an observational study or an experiment.

1. A council asks 500 randomly chosen adults how they travel to work.
2. A doctor records the diet of 2000 adults and checks their blood pressure every year for ten years.
3. A teacher gives half of her class, chosen by a coin, a new way of learning spellings, and tests both halves after a month.
4. A shop counts how many people buy fruit on rainy days and on dry days.