Unit 1: Measures of Central Tendencies

Andy has grades of 84, 65, and 76 on three math tests. What grade must he obtain on the next test to have an average of exactly 80 for the four tests?

84 + 65 + 76+ x = 80 (average) 4 (4)(80) = 225 + x 320 = 225 + x -225 -225 95 = x Andy needs a 95 on his next test.

The weekly salaries of six employees at McDonalds are $140, $220, $90, $180, $140, $200. For these six salaries, find: (a) the mean (b) the median (c) the mode.

List the data in order: 90, 140, 140, 180, 200, 220 Mean: 90+ 140+ 140+ 180 + 200 + 220 = 161.66 6 Median: 90,140,140,180,200,220 The two numbers that fall in the middle need to be averaged. 140 + 180 = 160 2 Mode: The number that appears the most is 140

A tally was made of the number of times each color of crayon was used by a kindergarten class. Which measure of central tendency should the teacher use to determine which color is the favorite color of her class?

The favorite color would be the color appearing the most number of times. Use the mode.

A storeowner kept a tally of the sizes of suits purchased in her store. Which measure of central tendency should the storeowner use to describe the average size suit sold?

The measure of central tendency that should be used to describe average is mean. Mean is the average of a set of data.

The science test grades are posted. The class did very well. All students taking the test scored over 75. Unfortunately, 4 students were absent for the test and the computer listed their scores as 0 until the test is taken. Assuming that no score repeated more times than the 0's, what measure of central tendency would most likely give the best representation of this data?

The mode in this set would be 0 and these 0's are acting as outliers for the data. The median is least affected by outliers and would most likely give the more positive view of the grades. Averaging in 4 zeros would dramatically lower the mean.