Question

A jar contains a mixture of 20 black marbles, 16 red marbles, and 4 white marbles, all the same size. Find the probability of drawing a white or red marble on the first draw

Answer 1

How many marbles in the jar?

Answer 2

20

Answer 3

Better add again. 20 black + 16 red + 4 white = how many marbles?

Answer 4

40

Answer 5

Yes. How many of them are black or red?

Answer 6

20 black 16 red

Answer 7

How many is that in all?

Answer 8

36

Answer 9

Now remember: probability is successful outcomes divided by total outcomes. So there are 36 marbles that will give us success. And there are 40 possible outcomes. So what is the probability of success? (And of course, success is getting a red or black marble)

Answer 10

20/40 or 36/40

Answer 11

Which one?

Answer 12

20/40

Answer 13

How many marbles constitute success?

Answer 14

what do u mean ?

Answer 15

how many are left

Answer 16

If I draw a white marble is that success?

Answer 17

im confused now...

Answer 18

4 white if i add with the red would be 20

Answer 19

\[P=\frac{successful`outcomes}{all`outcomes}\]

Answer 20

P=20/40 am i wrong?

Answer 21

No

Answer 22

\[\[Probability ofred`or`black=\frac{number`of`red`and`black`marbles}{total`number`of`marbles}\]\]

Answer 23

So what is the probability of drawing a red or black marble?

Answer 24

36/40

Answer 25

Very good. Now reduce that fraction

Answer 26

9/10
but this are my choices
1/25
1/2
1