Can someone explain this to me.
Determine if each conclusion is valid or invalid for the given statements.
a. Some expensive books are mystery books. All mystery books are interesting.
Conclusion: Some interesting books are expensive.
Valid or invalid.
b. Some teachers are smart.
Some nice people are smart.
Conclusion: Some teachers are nice people.
Valid or invalid
How about using Venn diagrams?
Draw two intersecting circles, label one "mystery books", the other " expensive books"
Now draw a circle, called "interesting", intersecting the expensive circle, but totally surrounding the mystery circle.
your conclusion was "Some interesting books are expensive"
Do you see an overlap in the 'interesting' and the 'expensive' circles??