## Explanation

You might first think this problem can be solved with the AVERAGEIF or AVERAGEIFS function. However, because total pay per week is not part of the worksheet, we can't use these functions because they require a range.

Working from the inside out, we first calculate total pay for all weeks:

```
D5:I5*D6:I6 // total pay for all weeks
```

This is an array operation that multiplies hours by rates to calculate weekly pay amounts. The result is an array like this:

```
{87,63,48,0,12,0} // weekly pay amounts
```

Since there are 6 weeks in the worksheet, the array contains 6 values. This array is returned directly to SUMPRODUCT function:

```
SUMPRODUCT({348,252,192,0,48,0})
```

The SUMPRODUCT function then returns the sum of items in the array, 840. At this point, we have:

```
=840/COUNTIF(D5:I5,">0")
```

Next, the COUNTIF function returns a count of values greater than zero in the range D5:I5. Since 2 of the 6 values are blank, and Excel evaluates blank cells as zero, COUNTIF returns 4.

```
=840/4
=210
```

The final result is 840 divided by 4, which equals 210