Average travel time* for men = 27.2 minutes, women = 23.6 minutes

My calculations are the followings:

My Calculations

The problem is my calculated mean is 28.4 but chart says 27.2

I calculate the mean with this formula: (sum of products of midpoint and freq) / sum of freq

  • $\begingroup$ What travel time did you use for 'worked at home'? $\endgroup$
    – Glen_b
    Commented Feb 10 at 2:06
  • 1
    $\begingroup$ It might be that 'up to 5 minutes' includes up to 4m59s which makes 2m30s the midpoint, same for other intervals. That only gets the mean down to 28.04 though, your approximation assumes all data points in a bin are symmetric around its center, which likely doesn't hold here. Is there any reason you can't just use the reported mean? $\endgroup$
    – PBulls
    Commented Feb 10 at 6:06
  • $\begingroup$ @PBulls The reason is that I want to be able to calculate it myself. So maybe they calculated the mean with the actual data, right? $\endgroup$
    – Amir
    Commented Feb 10 at 16:11
  • $\begingroup$ @Glen_b I didn't include it, as the chart itself also excludes it. $\endgroup$
    – Amir
    Commented Feb 10 at 16:12
  • $\begingroup$ The first chart shows it as the last category $\endgroup$
    – Glen_b
    Commented Feb 10 at 22:51


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