Could somebody please help me?

What situation is an example of an observational study

The weight of full–grown tomatoes at a farm is modeled by a normal distribution with a standard deviation of 18.4 grams. the 95 percent confidence interval for the mean weight of the tomatoes is calculated using a sample of 100 tomatoes. what is the margin of error (half the width of the confidence interval)?

Are triangles the congruent? write the congruency statement.what is the congruency that proves they are congruent? what is the perimeter of ∆pqr?