Question

Carson drives to school the same way each day and there are two independent traffic lights on his trip to school. He knows that there is a 30% chance that he will have to stop at the first light and an 80% chance that he will have to stop at the second light. What is the probability that he will NOT have to stop at either light?

Answer 1

What's the percent chance he **won't have to stop at the first and second lights?

Answer 2

14%

24%

50%

80%

Answer 3

Those are your options for answers?

And I mean just looking at the problem. If there's a 30% chance she WILL have to stop at the first light, what's the percent chance she WON'T have to stop?

Answer 4

at either light

Answer 5

I get that.

If there's a 30% chance, 3/10 , she will have to stop at the first light, there's a 70% ( 100% - 30%) chance, 7/10 sh,e won't have to stop.

Similarly, if there's an 80% chance she will have to stop at the second light, what's the percent chance she won't have to stop?

Answer 6

50?

Answer 7

Nope. At each stop light the percent that she either will stop or won't stop has to add up to 100%. 50% + 80% = 130%

Answer 8

oh ok lol

Answer 9

100% - 80% = x

What's x?

Answer 10

20

Answer 11

20%, right, 2/10

So multiply the chance that she *won't have to stop at the first light - 70%, 7/10 - and the percent chance she *won't have to stop at the second light - 20%, 2/10

Answer 12

70*20?

Answer 13

Technically yes, (70%)(20%). But what do those mean? In fractions?

Answer 14

70% and 20% aren't just numbers. They're percents. That means something.

Answer 15

14% ? .7*.2?

Answer 16

bingo!

Answer 17

You are correct.

Answer 18

In a group of 1500 people, 585 have blood type A, 165 have blood type B, 690 have blood type O, and 60 have blood type AB. What is the probability that a person chosen at random from this group has type B blood?

Answer 19

oh and thank you :)

Answer 20

What do you think for the blood one?

Answer 21

i thought 11% as the answer

Answer 22

And you are right :)

Answer 23

yess!! :)

Answer 24

very nice ^_^

Answer 25

A lab is trying to determine if a new medication is effective at reducing acne breakouts. The results are displayed in the Venn Diagram below.

Answer 26

What is the probability that the person's skin cleared up given that they used the medication?

Answer 27

@AllTehMaffs

Answer 28

yeah, the 40 is throwing me off.... The sample size has to be more than 40 given the diagram methinks... 1 sec

Answer 29

ohh ok lol

Answer 30

That doesn't look right to me. I can't make sense of it :/ What are the choices?

Answer 31

10%

20%

30%

60%

Answer 32

You might want to tag someone else to make sure, but I'm pretty sure there's something wrong with that diagram. It's either labeled wrong or not set up properly, or I'm crazy. I'm sorry, I really don't know :/

Answer 33

can you tag someone?

Answer 34

A two-way frequency table shows grades for students in college and students in high school.

Answer 35

@dan815 Can you look at this Venn diagram? It feels like there's something inherently wrong with it; can't make sense of what it's trying to say...