Question

A box contains 9 red and 2 blue marbles. If you select one marble at random from the box determine the odds against selecting a red marble.

Answer 1

since there are 11 marbles in total, the odds are 9/11

Answer 2

ok is there any thing else to show how I could explain the answer

Answer 3

well the probability of picking a red marble depends on how many red marbles and the total number of marbles in the box. So if there are 9 red marbles out of 11 marbles, then there is a 9/11 chance of picking a red marble.

Answer 4

ok and thanks

Answer 5

Odds are not expressed the same as the actual probability of an event.
\[ \quad \textbf{Probability} = \frac{\text{# desired outcomes}}{\text{# total poss. outcomes}} \\ ~\\
\quad \textbf{Odds} = \frac{\text{# desired outcomes}}{\text{# undesired outcomes}} \]
So, when we refer to "the odds against selecting a red marble", we take the number of blue marbles over the number of red marbles.