Sharon D.

asked • 09/25/14

How to calculate mode for grouped data

Your solution to this problem doesn't make sense according to the definition of modal class.
 
On your resources  page http://www.wyzant.com/resources/lessons/math/statistics_and_probability/averages; for the example of Mode for Grouped Data, the solution for modal class is 10-12? Shouldn't that be 16-18 because that is the group with the highest frequency of 8?
 
Therefore, isn't your entire calculation for mode wrong?

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Manuela I. answered • 09/25/14

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You are very correct! the Modal class is 16 - 18. 
 
The Formula is correct though, and if you plug in the correct numbers you should get 17.2. Just by looking at the data, you should have been able to estimate ~17. 
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Sharon D.

Yes, what I meant is for Example 6, with that data set, they calculated the mode incorrectly at 11.25. Shouldn't this example be corrected on the website?
When I plug in the numbers into the mode formula, I get 17.38 as the mode.
L=16
f1=8
f0=2
f2=1
h=3
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09/25/14

Manuela I.

Yes  --  So I get the same as you. I initially got a denominator of 15 (instead of 13) 
 
16 + (8-2)/[(8-2)+(8-1)] * 3
 
16 + 6/(6+7)  *3
 
16 + 18/13 = 16 + 1.38462 = 16.385
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09/25/14

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