A sample of 20 students who had recently taken elementary statistics yielded the following informatin on brand of calculator owned (T = Texas instruments, H = Hewlett Packard, C = Casio, S = Sharp):

C S T C C S T T S C

C T T T H H S S C H

a. Estimate the true proportion of all such students who own a Texas Instruments calculator.

b. Of the 6 students who owned a TI calculator, 2 had graphing calculators. Estimate the proportion of students who do not own a TI graphing calculator.

solution:

as, mean is defined as sum of all the observations divided by total number of observations.

and , median is mid value of the data whether arranged in ascending order or descending order.

consider, roadsters:

2,3,4,5,6,7,8,9

mean =

also, median= , because number of observations is even, so median is mean of two mid values.

now, coming to bandits

2,3,4,5,6

mean =  

median = 4, as number of observations is odd.

so, roadsters has greater median as well mean than bandits.

→option a is true about the repairs performed on 2 types of cars:

bandits have lower median and mean than roadsters.