Marble collection

Question

Keri has a collection of different colored marbles. Some of the marbles are big, and some of the marbles are small. The chart below shows how many of each type of marble is in Keri's collection

 

Big marbles:

12 red marbles

7 blue marbles

10 green marbles

9 yellow marbles

 

Small marbles:

8 red marbles

14 blue marbles

4 green marbles

18 yellow marbles

 

A marble is selected at random from Keri's collection

 

A) what is the probability that the marble selected will be green?

 

B) what is the probability that the marble selected will be a big marble?

 

C) what is the probability that the marble selected will be big and green?

Answer 1

Big marbles:    12 red;    7 blue;  10 green;    9 yellow  = 38 marbles
 
Small marbles:  8 red;  14 blue;    4 green;  18 yellow  = 44 marbles

 

Situation: a marble is randomly selected.

 

Question A: what is the probability that marble will be green?

Answer: there are 14 green marbles of 82 marbles; 14 ÷ 82 = 0.171 = 17.1%

When we divide the number 1 by 0.171, we get 5.8. So the probability is 1 in 5.8

 

Question B: what is the probability that marble will be big?

Answer: there are 38 big marbles of 82; 38 ÷ 82 = 0.463 = 46.3%

When we divide the number 1 by 0.463, we get 2.15. So the probability is 1 in 2.15

 

Question C: what is the probability that the marble will be both big and green?

Answer: the probability of both events is the product of the individual probabilities.

That is, 0.171 x 0.463 = 0.079 = 7.9%

When we divide 1 by 0.079 we get 12.6.

So the probability is 1 in 12.6