S+841.9=1000 what does S stand for

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Someone answer this check out the image!

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours