Question

(11-2 Probability) A number picked at random from the numbers 1 through 15 is prime. Can someone please help me with this?

Answer 1

Write out the numbers 1-15. Identify those that are prime.
Write the ratio (number of numbers that are prime) / (total number of numbers)

Answer 2

got you

Answer 3

Are you still there?

Answer 4

Okay now now the probability I came up with is 7/15

Answer 5

But the answer say 2/5 :(

Answer 6

That is why I am so confused

Answer 7

Or if not, 6/15. Still not the answer

Answer 8

Which numbers, 1-15, have you identified as "prime?"

Answer 9

1, 2, 3, 5, 7, 11, 13,

Answer 10

Or if 1 isn't included, 6 prime numbers

Answer 11

I'd agree that all of those are prime. And yes, if you omit 1, you have 6 prime numbers.

6 prime numbers
-------------- = (6/15) = (2/5). Agree with that?
15 numbers total

Answer 12

how does 6/15 = 2/5? How do you simplify that?

Answer 13

Can you divide 3 into 6?
Can you divide 3 into 15?

If so, what do you get, in each case?

Answer 14

Oooooooh O_O

Answer 15

You divided by 3 O_O

Answer 16

Thank you so much :D

Answer 17

You bet I did. Actually, I divided both 6 and 15 by 3.

You're welcome!

Answer 18

Oh thank you for saving me from this torment XD

Answer 19

Just kidding I love math!