Note that the 4 collections of questions have been posted in the Google+ space.
You may click at the LINK to access the page.
All are expected to visit the questions to check the working.
Click at each photo to view the working.
You may not have ample time to attempt all the questions; you may go through the working actively thinking of how you would approach the questions.
Some of the working presentation have errors, and our objective is to try surfacing those errors to remind ourselves not to commit the same mistake again.