Maths Questions

Question

Dot plot shows the number of vehicles per minute crossing an intersection during a period of 20 minutes.

The dot plot looks like:

• •

• •

• • •

• • • • • •

• • • • • • •

2 3 4 5 6 7 8 9 10

A) What is the mode?

B) What is the range?

C) What is the median?

D) Where are the scores clustered?

E) Calculate the mean correct to one decimal place.

F) Which score is an outliner?

Answer 1

bimodal: 2 modes, 7 and 8

range = max-min = 10-2 = 8

median = the middle number (or the average of 2 middle numbers if there are an even number of numbers) = 7 crossings per every 20 minutes

clustered over 7 and 8

mean = arithmetic average or average weighted by frequency: (1x2 + 1x4 + 3x5 + 2x6 + 5x7 + 5x8 + 2x9 + 1x10)/(1+1+3+2+5+5+2+1) = (2+4+15+12+35+40+18+10)/20 = 136/20 = 68/10 = 6.8 (if I did the arithmetic correctly)

No likely outliers, but if there is one it's 3. It's furthest from the mean, mode or median.