Percentage by month

I am trying to calculate the average percentage based on the month the score was received.

The average percentage for John Smith in October was 98.385. How do I calculate that as a formula?

I know how to do an average however I only want to count the ones for the relevant month which is where I run into confusion.

There is an example attached.

Will you please attach a sample Excel workbook? We are not able to work with or manipulate a picture of one.

1. Make sure that your sample data are REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired solution is also shown (mock up the results manually).

3. Make sure that all confidential data is removed or replaced with dummy data first (e.g. names, addresses, E-mails, etc.).

4. Try to avoid using merged cells as they cause lots of problems.

Unfortunately the attachment icon doesn't work at the moment, so to attach an Excel file you have to do the following: just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Please pay particular attention to point 2 (above): without an idea of your intended outcomes, it is often very difficult to offer appropriate advice.

Take a look at the averageifS() function for this

October

=AVERAGE(IF((MONTH(g2:g8)=10)*(YEAR(g2:g8)=2016),c2:c8))
then press shift+ctrl+enter

November
=AVERAGE(IF((MONTH(g2:g8)=11)*(YEAR(g2:g8)=2016),c2:c8))
then press shift+ctrl+enter

You are probably importing this from another application? I say this because your dates in G are not really dates, they are text - you need to make them dates 1st.
Also, when working with dates, it is almost always better to use real dates throughout, so change the month names in your extract table to real dates - format to just show months if needed.
Below I have changed according to my suggestions. I added a helper column to extract the date

	A	B	C	D	E	F	G	H
1	Agent	Score	Percentage	Name	Email Address	Survey ID	Date of Survey
2	John Smith	N/A	N/A	Angelina Jolie	123@fake.com	11111	30/10/2016 01:54 PM	10/30/2016
3	John Smith	N/A	N/A	Jane Doe	123@fake.com	11111	25/10/2016 08:23 PM	10/25/2016
4	John Smith	30	96.77%	John doe	123@fake.com	11111	25/10/2016 08:20 PM	10/25/2016
5	John Smith	N/A	N/A	Peter Pan	123@fake.com	11111	14/10/2016 09:57 PM	10/14/2016
6	John Smith	31	100.00%	Captain Hook	123@fake.com	11111	10/10/2016 08:54 AM	10/10/2016
7	John Smith	19	61.29%	James Franco	123@fake.com	11111	29/11/2016 04:47 AM	11/29/2016
8	John Smith	26	83.87%	Marvin Gaye	123@fake.com	11111	27/11/2016 05:48 PM	11/27/2016
9	John Smith	28	90.32%	Hawkeye	123@fake.com	11111	20/11/2016 06:09 AM	11/20/2016
10	John Smith	31	100.00%	Hulk	123@fake.com	11111	11/11/2016 11:02 PM	11/11/2016
11	John Smith	31	100.00%	Captain America	123@fake.com	11111	11/11/2016 08:30 PM	11/11/2016
12	John Smith	25	80.65%	Ironman	123@fake.com	11111	06/11/2016 01:18 PM	11/6/2016
13	John Smith	30	96.77%	Black Widow	123@fake.com	11111	05/11/2016 11:14 AM	11/5/2016
14	John Smith	31	100.00%	Spiderman	123@fake.com	11111	02/11/2016 10:49 PM	11/2/2016
15
16		Average Score
17		John Smith
18	July	N/A
19	August	N/A
20	September	N/A
21	October	98.39%	98.39%
22	November	89.11%	89.11%
23	December
24	January
25	February
26	March
27	April
28	May
29	June

H2=DATEVALUE(MID(G2,4,2)&"/"&LEFT(G2,2)&"/"&MID(G2,7,4))
copied down

A18:A29 are real dates now, so...
C18=IFERROR(AVERAGEIFS($C$2:$C$14,$A$2:$A$14,$B$17,$H$2:$H$14,">="&$A18,$H$2:$H$14,"<="&EOMONTH(A18,0)),"")
copied down

Note how I included the guys name in teh table so you can reference it