Sums of Independent Random Variables

Click For Summary
SUMMARY

The discussion centers on calculating the probability that the average IQ of 10 randomly selected students from a college, where the IQ distribution is N(110,16), is at least 112. The initial calculation incorrectly used the standard deviation instead of the standard error. The correct approach involves using the standard error, calculated as the standard deviation divided by the square root of the sample size, leading to a final probability of 0.0571, aligning with the textbook answer.

PREREQUISITES
  • Understanding of normal distribution, specifically N(μ, σ²)
  • Knowledge of standard error calculation
  • Familiarity with probability concepts and calculations
  • Ability to use statistical functions, such as the inverse of the cumulative distribution function (I)
NEXT STEPS
  • Study the concept of standard error and its importance in sampling distributions
  • Learn how to apply the Central Limit Theorem in practical scenarios
  • Explore the use of statistical software for calculating probabilities
  • Investigate the properties of normal distributions and their applications in hypothesis testing
USEFUL FOR

This discussion is beneficial for students in statistics, educators teaching probability theory, and anyone involved in data analysis requiring an understanding of sampling distributions and normal probabilities.

WHB3
Messages
19
Reaction score
0

Homework Statement



The distribution of the IQ of a randomly selected student from a certain college is N(110,16). What is the probability that the average of the IQ's of 10 randomly selected students from this college is at least 112?


Homework Equations



I think we need P(Sample Mean - 110 >= 2)


The Attempt at a Solution



My solution was Probability = (112-110)/1.6 = 1.25; 1-I(1.25)= 1-.8944 =.1056

The answer in the book is .0571, so I know I'm going wrong somewhere.

Any ideas?
 
Physics news on Phys.org
No need to respond, guys. I have found the error of my ways. I forgot that the std Error equals the std deviation divided by the sqr. root of the sample size. Working with that would have brought me to the Probability = 1-I(1.58) = 1-1.9429 =.0571. Thanks, anyway!
 

Similar threads

Replies
2
Views
2K
Replies
7
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 30 ·
2
Replies
30
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 22 ·
Replies
22
Views
2K