The trunk diameter, in centimeters,  of a certain variety of pine tree is represented by X~N(150, 30).  What is the z-score for a tree with a diameter of 180 centimeters?

Q: The average percentage of correct responses on last semester's Midterm was 78%.  What can be said…

A: The standard normal distribution: A continuous random variable Z is said to follow standard normal…

Q: As an economics class project, Debbie studied a random sample of 14 stocks. For each of these…

A:

Q: A survey of 225 residents of a neighborhood indicates that 135 of them are in favor of having a…

A: Given, total residents = 225 135 are in favor of block party.

Q: Helga scored in the 70th percentile rank on an exam. If 300 students took the exam, how many…

A: Given: percentile rank of Helga: 70th           total number of students who took exam: 300 students…

Q: Alex is 80th in his class of 320 students. What is his percentile rank in class?

A: Data given p=80, n=320

Q: John calculated r -.44 for a set of n 10 pairs of values that represent the number of absences from…

A: Given that r = -0.44 midterm exam score ( y )   number of absences from class (x)

Q: Calculate the average job gains using the numbers you obtain, 36,239.

A: The given numbers of jobs are 36 and 239.

Q: Residents in a city are charged for water usage every three months. The water bill is computed from…

A: Given

Q: Marla scored 70% on her last unit exam in her statistics class. When Marla took the SAT exam, she…

A: solution:  The difference is that Marla’s exam in her statistics class was graded by percent of…

Q: The mean of 12 numbers is 48. Removing one of the numbers causes the mean to decrease to 45. What…

A: Measures of Central Tendency: A measure of central tendency represents the central value or typical…

Q: A class uses weighted averages to calculate your course grade.  Homework is worth 75% of your course…

A: The formula of weighted average is given by,  Xm = ∑xw/∑w = sum of (number × weighing factor)/sum…

Q: A survey of 700 non fatal accidents showed that 287 involved defective equipment.  Find a point…

A: Given

Q: What percentage of people has an IQ score greater than 157

A: Z is known as standard normal variable Z=(X-mean)/standard deviation

Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.