# Gaussian Distribution

• Apr 17th 2007, 03:09 PM
thefirsthokage
Gaussian Distribution
The strength levels of a group of Martians follows Normal distribution with a mean of 75kgf and a std. dev. of 5kgf.

(a) How many Martians do you expect to meet before you find one with a strength level greater than 72 kgf?

(b) In a group of 5 Martians, what is the probability that exactly 4 Martians have strength levels greater than 72 kgf?

(c) 4 Martians are trying to open a huge stone door which will open only if all of their individual strength levels are greater than 72 kgf. What is the probability that they will open the door?

EDIT: Never mind I figured out (a) and (c). Still need help on (b), though. Thanks. I'll probably kick myself for not seeing it, but oh well.
• Apr 27th 2007, 12:42 PM
CaptainBlack
Quote:

Originally Posted by thefirsthokage
The strength levels of a group of Martians follows Normal distribution with a mean of 75kgf and a std. dev. of 5kgf.

(a) How many Martians do you expect to meet before you find one with a strength level greater than 72 kgf?

(b) In a group of 5 Martians, what is the probability that exactly 4 Martians have strength levels greater than 72 kgf?

(c) 4 Martians are trying to open a huge stone door which will open only if all of their individual strength levels are greater than 72 kgf. What is the probability that they will open the door?

EDIT: Never mind I figured out (a) and (c). Still need help on (b), though. Thanks. I'll probably kick myself for not seeing it, but oh well.

Calculate the probability p(72) that a martian has strength > 72 kgf. Then
the number with strength >72 kgf in a sample of 5 has a binomial distribution
B(p(72), 5). So prob of 4 having strength >72 kgf is b(4, p(72), 5).

RonL
Given a text passage, determine:
    1. If it contains a mathematical question (including word problems or calculations)
    2. If an answer to that mathematical question is provided in the text

First, describe the content structure you found in 1-2 sentences.

Then provide your analysis in the following format:
TYPE: <one of the following values>
- NO_QUESTION
- SINGLE_QUESTION
- SINGLE_QUESTION_WITH_ANSWER
- MULTIPLE_QUESTIONS
- MULTIPLE_QUESTIONS_WITH_ANSWERS
system
# Gaussian Distribution

• Apr 17th 2007, 03:09 PM
thefirsthokage
Gaussian Distribution
The strength levels of a group of Martians follows Normal distribution with a mean of 75kgf and a std. dev. of 5kgf.

(a) How many Martians do you expect to meet before you find one with a strength level greater than 72 kgf?

(b) In a group of 5 Martians, what is the probability that exactly 4 Martians have strength levels greater than 72 kgf?

(c) 4 Martians are trying to open a huge stone door which will open only if all of their individual strength levels are greater than 72 kgf. What is the probability that they will open the door?

EDIT: Never mind I figured out (a) and (c). Still need help on (b), though. Thanks. I'll probably kick myself for not seeing it, but oh well.
• Apr 27th 2007, 12:42 PM
CaptainBlack
Quote:

Originally Posted by thefirsthokage
The strength levels of a group of Martians follows Normal distribution with a mean of 75kgf and a std. dev. of 5kgf.

(a) How many Martians do you expect to meet before you find one with a strength level greater than 72 kgf?

(b) In a group of 5 Martians, what is the probability that exactly 4 Martians have strength levels greater than 72 kgf?

(c) 4 Martians are trying to open a huge stone door which will open only if all of their individual strength levels are greater than 72 kgf. What is the probability that they will open the door?

EDIT: Never mind I figured out (a) and (c). Still need help on (b), though. Thanks. I'll probably kick myself for not seeing it, but oh well.

Calculate the probability p(72) that a martian has strength > 72 kgf. Then
the number with strength >72 kgf in a sample of 5 has a binomial distribution
B(p(72), 5). So prob of 4 having strength >72 kgf is b(4, p(72), 5).

RonL
user
The text passage contains a series of questions related to the probability and statistics of Martian strength levels, which follow a normal distribution. The user has solved parts (a) and (c) but is seeking help with part (b).

TYPE: MULTIPLE_QUESTIONS_WITH_ANSWERS

However, since the user has solved parts (a) and (c) and is only asking for help with part (b), the more accurate classification would be:

TYPE: SINGLE_QUESTION_WITH_ANSWER