Question

Eli has 7 black pens and 5 blue pens in his desk drawer. He also has 3 yellow highlighters, 2 green highlighters, and 5 pink highlighters in his pencil case. If he chooses one pen and one highlighter without looking, what is the probability that he will get a black pen and he will not get a green highlighter?

Answer 1

@terenzreignz

Answer 2

What's the probability that he gets a black pen?

Answer 3

1/22

Answer 4

How do you get 22? There are only 7 black pens and 5 blue ones...

Answer 5

oh sorry i added all the numbers. if theres 11 total pens

Answer 6

Nope, still not 11 :D

Answer 7

7+5, Kayy...
Wake up :P

Answer 8

12

Answer 9

Haha i am half sleep to be honest

Answer 10

Why, where are you from?

And LOL
So, 12 pens in total, how many black pens?

Answer 11

Theres 7 black pens total

Answer 12

So, what are the odds that he picks a black pen, without looking?

Answer 13

7/12 or 1/12

Answer 14

Only one of those... so which is it?

Answer 15

7/12

Answer 16

That's right :)
Now, how many highlighters total?

Answer 17

10

Answer 18

And how many are NOT green?

Answer 19

8 because theres only 2 green highlighters

Answer 20

That's correct.
Now, what are the odds that he selects a non-green highlighter, then?

Answer 21

including the whole total of highlighters

Answer 22

Of course.

Answer 23

2/10

Answer 24

@terenzreignz

Answer 25

Nope. That's the odds of picking a green highlighter... what are the odds then of NOT picking a green highlighter?

Answer 26

ummm ??

Answer 27

Earlier, since there were 7 black pens and 12 pens total, the odds of getting a black pen was 7/12, right?

Answer 28

Yeah but theres only 2 green highlighters

Answer 29

Yeah, but we're not shooting for a green highlighter, in fact the opposite... we DON'T want to pick a green highlighter, that's why I asked you how many highlighters were NOT green... get it?

Answer 30

Ohh okay so in that case if we take out the 2 greens ita 8 total

Answer 31

8.3% is my answer ?

Answer 32

8.3? Slow down...
what are the odds that he gets a non-green highlighter?

Answer 33

I was looking at my answer choices.

Answer 34

2/8 idk lol

Answer 35

No. How did you get 7/12?
You divide the number of favourable outcomes (in this case, a black pen) by the TOTAL NUMBER of outocmes...
There are 7 black pens (favourable)
and there are 12 pens total
Hence, 7/12 odds of getting a black pen.

Do the same for the highlighters...
Favourable outocme is NOT a green highlighter, so how many is that?

Answer 36

i got 7/12 because there 7 black pens and 12 total pens .

Answer 37

Yes. So do the same with the number of non-green highlighters and the total number of highlighters.

Answer 38

theres 10 total highlighters right ?

Answer 39

Yes.

Answer 40

if theres 2 green how comes its not 2/10

Answer 41

Reread your question.

Answer 42

-____________________________________________-

Answer 43

Come on, just read it again, the answer to "why is it not 2/10" is there.

Answer 44

because it says black pens and green pens is it 7/12 again or 7/10

Answer 45

46.7%
11.7%
33.3.%
8.3%

Answer 46

Are we looking for the probability that he picks a green highlighter?

Answer 47

no

Answer 48

Then, what were we looking for if not the odds that he picks a green highlighter?

Answer 49

1/10

Answer 50

0/10

Answer 51

Not proceeding until you answer that question ^

Answer 52

omg i give up

Answer 53

Well, you simply can't do that when faced with an actual exam, now can you? :)
Come on, I'm simply making the utmost sure that you understand how to do this.

Answer 54

I know but i cant get the freakin odds or whatever you talking about.

Answer 55

odds are the same as probability.

Answer 56

I'm going to ask you one more time... what is the probability that he picks a NON-GREEN highlighter?

Answer 57

idk i already told you almost every answer and you still said no so idk what else could it be

Answer 58

Okay... so tell me, how did you get 7/12 for the probability that he picks a black pen?

Answer 59

because theres 7 black pens and 12 total pens. theres 10 total highlighter but 2 green ones , but your saying non green which takes out the 2

Answer 60

Because there are 7 black pens and 12 total pens, that's good.
You counted how many black pens there are, and divided it by the total number of pens.

Now, I asked you the odds of getting a non-green highlighter...
I don't see what's drastically different about this, you do something exactly the same...
count the number of non-green highlighters, and divide it by the total number of highlighters.

Answer 61

there are no non green there 2 green it says. so am i suposed to divde 7/12*2/10 or what because idk and im about to just skip this question iv been on it for 43 minutes

Answer 62

There are no non-green highlighters?

Answer 63

So the pink and the yellow highlighters are also green? -.-

Answer 64

in that case its 0/10 because theres still 10 total inless its 0/8

Answer 65

if theres NO NON GREEN , but in the passage its 2 GREEN HIGHLIGHTERS

Answer 66

Yes, there are two green highlighters, but they're not the ones Eli wants to pick, the questions wants the odds that he picks a non-green highlighter
IN OTHER WORDS
a PINK or a YELLOW highlighter.
Now, HOW MANY PINK AND YELLOW HIGHLIGHTERS ARE THERE?
What are the odds that he picks a PINK or a YELLOW highlighter?

Answer 67

8 total because theres 5 pink and 3 yellow

Answer 68

46.7%
11.7%
33.3.%
8.3%

Answer 69

I have work at 12;30 i need to hurry and finish i have 10 more questions to go.

Answer 70

Yes. So NOW do you know the odds of getting a non-green highlighter?
It's the same as the odds of getting a pink or yellow highlighter....

Answer 71

so its just 8

Answer 72

NO... that's the number of pink or yellow highlighters.

Answer 73

idk then ?

Answer 74

The number of black pens is 7
the odds of getting a black pen is 7/12

The number of non-green highlighters is 8
the odds of getting a non-green highlighter is...?

Answer 75

10 or 0

Answer 76

Nope. Try again.

Answer 77

wht is it ?

Answer 78

Okay, here's a hint ...
odds are never greater than 1.

Answer 79

is it 1

Answer 80

No.
An odds of 1 means it will definitely happen, and that's not the case...
You're not sure that he'll pick a non-green highlighter, because there are still two green ones...

Answer 81

I have to be at work soon so im just gnnah skip this one iv been on this problem for an hour and i still have a lot more to go and im very frustrated .

Answer 82

@terenzreignz