You begin a study with primary school children.You show them a box which contains 3 yellow,2 black,4 white and 3 clear buttons.Two buttons are taken one after the other at random from the box.What is the probability that both buttons are black?
A)1/6
B)1/16
C)1/60
D)1/66

Question

Quizplus · Accepted Answer

The total number of buttons is 3 + 2 + 4 + 3 = 12. The probability of picking one black button is 2/12 (or 1/6), and after taking one black button out, the probability of picking another black button is 1/11 (since there are now 11 buttons left and only one of them is black). The probability of both events happening is (1/6) * (1/11) = 1/66.

You Begin a Study with Primary School Children