Question 6: Isla has a box of counters. The table shows information about the shape and colours of the counters.
Shape
Aircle Triangle Square
Blues 6 2
Red
8 9 11
Colour
Isla picks a counter at random, looked at it and then returned it to the box.
(a) Given it is a circular counter, what is the probability that it was red?
David picks a counter at random, looked at it and then returned it to the box
(b) Given it is a blue counter, what is the probability that it was triangular?
Emily adds a number of red square counters to the box.
The probability of Emily picking a red square at random is now
2/3
(c) How many red square counters did Emily add to the box?