Needing on question one. i have formulas but am not really sure what goes where.

The force acting on a beam was measured under the same operating conditions and a sample of 5 data points was collected. this process was repeated by 3 observers. the pooled standard deviations of these 3 data sets was 1.21. determine the true mean force using all pooled data (with a 95% probability). the result should look like this: true mean = mean +/- margin of error

Could someone . i have tried to solve myself but my calculation is off

What is a neurotransmitter involved in mood reward, addiction, and motor behaviors?