Question

There are 5 blue marbles, 2 red marbles, and 3 green marbles in a bag.One marble is drawn at random. What is theprobability of selecting NOT a red marble? Your answer can be a fraction, decimal orpercent.

Answer 1

The total number of marbles in the bag is

`\begin{gathered} n(B)=5 \\ n(R)=2 \\ n(G)=3 \end{gathered}`

The total number of marbles will be

`\begin{gathered} n(S)=n(R)+n(B)+n(G) \\ n(S)=2+5+3 \\ n(S)=10 \end{gathered}`

Concept :

To calculate the probability of selecting not a marble, we will use the formula below

`Pr(\text{not red)=1 -Pr(R)}`
`\begin{gathered} Pr(R)=(n(R))/(n(S)) \\ Pr(R)=(2)/(10) \end{gathered}`

Hence,

The probability os selecting not red will be

`\begin{gathered} Pr(\text{not red)=1 -Pr(R)} \\ Pr(\text{not red)}=1-(2)/(10) \\ Pr(\text{not red)=}(10-2)/(10) \\ Pr(\text{not red)=}(8)/(10) \\ Pr(\text{not red)}=(4)/(5) \end{gathered}`

Hence,

The final answer is = 4/5