Average measurements from seconds to minutes

[Sunday]

Hi all, I have recorded my measurements in 30 seconds intervals (device max interval). I am trying to average the observations at least for 15 minutes intervals.

library(dplyr)
summarize(group_by(mp_4_1316,cut(mip_4_1316$Time, breaks="15 min"),mean(pm25))

but I am getting the following error message
Error: unexpected symbol in:summarize(group_by(mp_4_1316,cut(mip_4_1316$Time, breaks="15 min"),mean(pm25))

How can I average this into the desired interval?

Thanks

[Dobrokhotov1989]

I'm not sure, but in your code, you have 4 openings parenthesis ( and only 3 closings). Perhaps you need to add one more closing before mean(pm25).
If it doesn't help, please provide a reprex with a sample of your data. You can provide sample data using function dput() and coping the output from the console.