0580 P23 - Nov 2020 - Q11 - 4 marks
13402
A bag contains7 red,5 green and2 pink discs.
(a) Helen selects and replaces a disc140 times. Find her expected number of green selections. [2]
(b) She adds9 green and some pink discs. Green probability is now2/7. How many pink discs were added? [2]
