Science Buddies: "Ask an Expert"

I am doing the project about the onset and decay time of sunspot cycles, here is the link: https://www.sciencebuddies.org/science- ... om=TSW#EP4
I am almost finished, I am just confused with one aspect. I am supposed to calculate the onset and decay, however the instructions are very vague.

Calculating Onset Time and Decay Time

Now you have all the information you need to calculate the onset time and decay time for each solar cycle. With what you've learned about spreadsheets so far, you should be able to do this on your own.

In addition, you should have Excel calculate the difference between the onset time and decay time for each solar cycle.

Finally, for all three values (onset time, decay time and difference), calculate the average and standard deviation for all 22 solar cycles.
Is there a difference?

Do I subtract the monthly maximum and minimum sunspot numbers, or am I subtracting the years where the maximums and minimums are occurring?

Quick help would be much appreciated. Unfortunately my project is due tomorrow.
I have everything else finished, except for this.

Thank you in advance for the help.

What an interesting project! Reference back to the end of the introduction, and they define onset and decay times:

The onset time is the time from the beginning of the cycle to the maximum of the cycle.
The decay time is the time from the maximum of the cycle to the end of the cycle.

You should be extracting beginning, maximum, and end of cycle times from your data, and the calculations should be easy from there.

I hope this helps. Certainly write back if you have any further questions. Good luck!