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### Course: Grade 7 math (FL B.E.S.T.)>Unit 8

Lesson 5: Comparing and sampling populations

# Comparing distributions with dot plots (example problem)

Sal examines two distributions in dot plots to draw conclusions about the times of Olympic swimmers. Created by Sal Khan.

## Want to join the conversation?

• Why distribution in dot plot?
• The answer to the semifinal round is 53.3375, and the final round is 53.1875, I don't know if I got it right, is it only 0.15 seconds?
• I calculated a difference of 0.25. It seems like you've got the process down but you made a small mistake in your calculation. Nothing to worry about.
• why is it on a dot plot
• Because it is on a dot plot.
• Just to clarify.... the lower the value = better 100meter time = faster those "dots" swam. Am I correct??
• ya that's right
• could you explain more this statement "That does look to be true. We see in the semifinals, a lot of the times were clumped up right around here at 53.3 seconds and 53.5 seconds. The high time isn't as high as this time. The low time isn't as low there. So the final round is definitely-- they vary noticeably more"
• Sal means that if you look at the graph for the semifinals, the fastest time recorded isn't as fast as the fastest time for the finals. Same for the slowest time recorded, that's why the final round varies noticeably more in range.
hope this helps!
• Sal was wrong about the statment "one of the swimmers was disqualified from the finals" because he said that no one was disqualified from the SEMIFINALS! NOT THE FINALS!
• This only shows a dot plot while the questions have a graph pls help me dude whats goin on here O-O
• The swimmers had a faster time in the finals? If you do the math the finals averaged 53.18 and the Semi-Finals averaged 53.31. So that answer is incorrect.
~Aubrey