Question

What is the interquartile range for the data set? 89, 91, 95, 112, 118, 83, 85, 104, 118, 125, 134, 138 Enter your answer in the box.

Answer 1

1. First, put the range in order and then divide the set into quarters. In this case, quartiles are between numbers.83, 85, 89,   l    91, 95, 104,  l   112, 118, 118,  l  125, 134, 138Q₁ = (89 + 91)/2 = 90Q₂ = (104 + 112)/2 =108Q₃ = (118 + 125)/2 = 121.5Interquartile range (IQR) = Q₃ - Q₁                                        = 121.5 - 90                                 IQR = 31.52. To find the standard deviation follow the simple steps.Formula in finding the standard deviation: (see attached file)     Step 1. Work out the simple average of the numbers (mean)                212 + 249 + 212 + 248 + 239 + 212 + 216 + 234 + 248                                                 9              = 2070                     9mean (μ) = 230        Step 2. Subtract the mean on each number and square the result.212 - 230 = (-18)² = 324249 - 230 = ( 19)² = 361212 - 230 = (-18)² = 324248 - 230 = (18)²  = 324239 - 230 = (9)²    = 81212 - 230 = (-18)² =324216 - 230 = (-14)² =196234 - 230 = (4)²    =16248 - 230 = (18)²  =324
     Step 3. Add all the squared results and get the mean.                  2274                     9       Variance = 252.6666667    Step 4. Get the square root of the variance.                  √252.6666667                  = 15.89549202