Cara computes the mean and variance for the set 87, 46, 90, 78, and 89. she finds the mean to be 78. her steps for finding the variance are shown below.
variance squared = startfraction (87 minus 78) squared + (46 minus 78) squared + (90 minus 78) squared + (78 minus 78) squared + (89 minus 78) squared over 5 endfraction
variance squared = startfraction (9) squared minus (32) squared + (12) squared + 0 squared + (11) squared over 5 endfraction
variance squared = startfraction 81 minus 1,024 + 144 + 0 +121 over 5 endfraction
variance squared = startfraction negative 678 over 5 endfraction = negative 135.6
what is the first error cara made in computing the variance?