Array to avg rows meeting criteria in one column and single-row (non array) in 2nd column

Hello! Attached is a file with dates in F, and the daily averages for those five dates in column G. An array formula works perfectly to calculate the average for the day of the ppb in column E, even when there are different numbers of samples (rows) in the day being calculated. However, i want to run this as it is now, but excluding those rows that have any value in the flag column D. I suspect this is not working because i need a corresponding array for the inner AND criterion. Can you suggest how I can do this? I need to keep this as simple as possible as I work for computer and programming-averse people who nevertheless need to construct such tables themselves with different numbers of variables. THANK YOU!

try:

Formula:

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wow, cool, i had no idea of iserror or averageifs. it works! thank you v. much.

Glad to help
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