Find next: 5, 10, 20, 40, ?

A walks 10 km North, turns right walks 5 km, turns right walks 10 km. How far from start?

Statements: Some questions are easy. Some easy are solved. All solved are correct. Some correct are verified. Conclusion: Some questions are verified. Is this valid?

Which hormone is produced by the pancreas to lower blood glucose?

If P is the brother of Q, and R is the daughter of Q, how is P related to R?

Statements: All boys are students. Some students are intelligent. All intelligent are hardworking. Some hardworking are successful. Conclusion: Some boys are successful. Is this valid?