Okay. I've forgotton how to do this one...
i) The average of 8 numbers is 15. When a 9th number is added, the average becomes 12. What is the 9th number.
And now for something a little harder..
ii)Write an expression for n
(1+ 1/2)(1+ 1/3)(1+ 1/4)...(1+ 1/n)
iii) A semicircle with...