Can somebody help with me two probability problems?

[ctark]

First one is.

A cellular phone manufacturer randomly selects 8 of every 100 phones from the assembly line and tests them. If at least 7 out of the 8 selected pass inspection then the batch of 100 is considered acceptable. Find the probability tht the batch is considered acceptable if there are 4 defective phones in a batch.

I set the problem up as

(96 C 8 + (96 C 7 x 4 C 1))/100 C 8

But it came out with a approx 1.009, which is wrong because it needs to be below 1.

Second one:

A fair six sided die is rolled 10 times. What is the probability that the roll of 2 will occur exactly 6 times?

I have yet to find an example to give me clues how to do this.

 

[ctark]

I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

 

[Vehemence]

Oh that's easy. It's 42.14

 

[SunnyD]

Probably.

 

[darkxshade]

110%

 

[rivan]

Originally posted by: ctark
I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

It's not 11 am (cst) yet. Most of them are sleeping in, comfortable on their money-stuffed mattresses, next to their supermodel wives.

 

[BigJ]

On the second one, you need to compute the odds of it rolling 2 (1/6) 6 times , and rolling it not 2 (5/6) the other 4 times. It seems fairly intuitive, but the 2nd part is where most people slip up.

 

[aesthetics]

Originally posted by: ctark
I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

GTFO.

Maybe we just don't want to help some punk who posts his homework on the internet.......

 

[UncleWai]

Hi I will do those questions for you if you agree to let me do your girlfriend too.

It seems you haven't even tried to put common sense into the probability concept and just tried to plug some numbers into formulas that don't apply.
First question, what are the scenarios that the test will pass?
7 of 8 tested functional, 8 of 8 tested functional. Probability of picking 1 from the batch to be functional = 96/100. probability of defective is 1 - P(functional) = 4/100

Second question, apply the same complimentary probability. Each roll of the dice is independent.

 

[ctark]

Originally posted by: UncleWai
Hi I will do those questions for you if you agree to let me do your girlfriend too.

It seems you haven't even tried to put common sense into the probability concept and just tried to plug some numbers into formulas that don't apply.
First question, what are the scenarios that the test will pass?
7 of 8 tested functional, 8 of 8 tested functional. Probability of picking 1 from the batch to be functional = 96/100. probability of defective is 1 - P(functional) = 4/100

Second question, apply the same complimentary probability. Each roll of the dice is independent.

On the cell phone problem I did it the same way shown above on my homework and it was counted correct, but he could just have overlooked it. I redid the problem in my calculator and i got a .96xxxx of probability acceptable. I believe thats right.

 

[puffff]

The first one basically boils down to a much simpler problem. Given 8 phones, and knowing that each one has a 1/25 chance of being defective, what are the chances that none of them are defective?

(24/25) ^ 8 ought to be your answer.

 

[BigJ]

Originally posted by: puffff
The first one basically boils down to a much simpler problem. Given 8 phones, and knowing that each one has a 1/25 chance of being defective, what are the chances that none of them are defective?

(24/25) ^ 8 ought to be your answer.

Your restrictions are too severe.

1 of the 8 is allowed to be defective for the batch to pass.

 

[DrPizza]

Originally posted by: BigJ
On the second one, you need to compute the odds of it rolling 2 (1/6) 6 times , and rolling it not 2 (5/6) the other 4 times. It seems fairly intuitive, but the 2nd part is where most people slip up.

Don't forget that there's more than one order to have it happen.

 

[potoba]

Originally posted by: ctark
I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

Will give you the answers when i have time.

 

[jonks]

Originally posted by: ctark
I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

the smart people like me picked careers where we don't have to do math problems. but the answers are

1) mary poppins
2) pickles

 

[Epic Fail]

Originally posted by: DrPizza

Originally posted by: BigJ
On the second one, you need to compute the odds of it rolling 2 (1/6) 6 times , and rolling it not 2 (5/6) the other 4 times. It seems fairly intuitive, but the 2nd part is where most people slip up.

Don't forget that there's more than one order to have it happen.

Yup, no 2 isn't as easy as it seems.

OP, read this.

http://en.wikipedia.org/wiki/H...geometric_distribution

 

[D1gger]

Originally posted by: dNor
Oh that's easy. It's 42.14

With rounding, the answer is 42. The answer is always 42.

 

[tasmanian]

Am I the only one to notice the problem in the title?

 

[GagHalfrunt]

Originally posted by: ctark
I figured with all the smart people here with 7 figure incomes somebody would know how to do this.

People with 7 figure incomes didn't get there by doing someone elses homework for them.