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...

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

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 ...

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...