What are the odds against choosing a blue marble from a bag that contains two blue marbles, one green marble, seven white marbles, and four red marbles?

12:2

2:14

14:2

10:2

Odd against will be 12 : 2

So option (a) will be correct option

Step-by-step explanation:

We have given that a bag contain two blue marbles, one green marble, seven white marbles and four red marbles

So total number of marbles = 2+1+7+4 = 14 marbles

We have to choose blue marbles

We know that

The odds against - the ratio of the number of ways that an outcome cannot occur compared to in how many ways it can occur.

So

Odds against = Number of failures: Number of successes

Number of failures = 14 - 2 = 12

So odd against = 12 : 2

So option (a) will be correct option