What are the differences between bottom-up and top-down estimating approaches?

Question#1 (one page)What are the differences between bottom-up and top-down estimating approaches? Determine advantages and disadvantages for using each approach. Under what conditions would you prefer one over the other? Provide a specific example to support your response. Question#2 (one page)Share a source you will use in writing your resource scheduling methods analysis paper. Provide an APA citation for the source. Provide a brief summary of the source, an evaluation of the merits or reliability of the source, and your personal reaction to the contents of the source such as whether or not you learned anything new regarding project management.