Math 221 - Study guides, Class notes & Summaries

From a random sample of 58 businesses, it is found that the mean time the owner spends on administrative issues each week is 21.69 with a population standard deviation of 3.23. What is the 95% confidence interval for the amount of time spent on administrative issues? A. (19.24, 24.14) B. (21.78, 22.60) C. (20.86, 22.52) D. (20.71, 22.67) C. (20.86, 22.52) If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86, what is the margin of error? 2.52 5.0...

If A is an m × n matrix and if the equation Ax=b is inconsistent for some bb in Rm, then A cannot have a pivot position in every row.True If the equation Ax=b is inconsistent, then b is not in the set spanned by the columns of A.True If A is an m × n matrix whose columns do not span Rm, then the equation Ax=b is inconsistent for some b in Rm.True Any linear combination of vectors can always be written in the form Ax for a suitable matrix A and vector x.True The equation Ax=b is con...

From a random sample of 58 businesses, it is found that the mean time the owner spends on administrative issues each week is 21.69 with a population standard deviation of 3.23. What is the 95% confidence interval for the amount of time spent on administrative issues? A. (19.24, 24.14) B. (21.78, 22.60) C. (20.86, 22.52) D. (20.71, 22.67) Correct Answer C. (20.86, 22.52) If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86, what is the margin of error?...

(CO 1) A survey of 128 DeVry statistics students found that 83% read the announcements each week. What is the population and what is the sample? Population: all statistics students reading announcements weekly; Sample: the 128 DeVry statistics students Population: DeVry statistics students; Sample: the 83% that read the announcements weekly Population: all statistics students; Sample: 128 DeVry statistics students Population: DeVry statistics students: Sample: 128 DeVry statistics st...

System of Equations: Consistent/Inconsistent Has a solution (or many)= Consistent No solution= inconsistent Matrices: Echelon Form Requirements 1. All nonzero rows are above zero rows 2. each leading entry of a row is in a column to the right of the leading entry of the row above it 3. all entries in a column below a leading entry are 0s Matrices: Reduced Echelon Form Requirements all 3 of Echelon Form 4. each leading entry in each nonzero row is a 1 5. each leading 1 is the only nonzer...

Understand the problem-reword Devise a plan- identify subgoals, think of the best method (such as making a table or guess and check) Carry out the plan- stay organized and show all work Look back- check your work and make sure you answered the question (working backwards) Polya's problem solving method counting numbers {1,2,3...} Natural numbers includes zero {0,1,2,3...} Whole numbers includes negative numbers {-1,-2,-3,0,1,2,3...} Integers (fancy R) all numbers including decimals ...

cofactor definitioncij(A) = (-1)^(i+j) det(Aij) (-1)^(i+j) is called the sign of the (i,j)-position if A has a row or column of zeros,det(A) = 0 if two distinct rows (or columns) of A are interchanged, the determinant of the resulting matrix is-detA if a row (or column) of A is multiplied by a constant u, the determinant of the resulting matrix isu(detA) if two distinct rows (or columns) of A are identical, detA =0

Difference between categorical and quantitative data Correct Answer Quantitative variables provide numerical information. Categorical variables yield data that can only be considered as categories. Differences in the definitions of a Parameter, Population, Statistic and a Sample Correct Answer Parameter: Numbers that summarize data from a population Population: Entire collection of a group Statistic: The probability of obtaining a result or numbers that summarize the data from a sample S...