When analysing normally distributed data, standard deviation can be used in conjunction with the mean in order to calculate data intervals. If = mean, S = standard deviation and x = a value in the data set, then. 1  about 68% of the data lie in the interval: . 2  about 95% of the data lie in the interval: + 2S.
Little gem arborvitae (Thuja occidentals 'Little Gem') is an evergreen shrub that keeps its brilliant color and foliage all year long. Growing 1 to 3 feet tall, little gem has medium texture and a slow growth rate. The dense dwarf shrub has a compact form and globose shape.
Growth rate: Slow to medium, with height increases of anywhere from less than 12 inches to 24 inches a year. Cost: 6 feet, $50. This evergreen acts as a great hedge, growing in a narrow, pyramid shape. Itâs a practical option, requiring little to no maintenance, and is ideal for a privacy screen or a windbreak.