Answer:
8.2
Step-by-step explanation
Tyhe formula for calculating the margin of error is expressed as;
![M\text{ = z}*\sqrt[]{(s^2)/(n)}](https://img.qammunity.org/2023/formulas/mathematics/college/8d3q58vq6xvi6kx9ufjd7yy2gqzp6bs6l1.png)
z is the z-score at 95% confidence interval =
s is the standard deviation = 40 pounds
n is the sample size = 92
Substitute
![M\text{ = }1.96*\sqrt[]{(40^2)/(92)}](https://img.qammunity.org/2023/formulas/mathematics/college/dtysstqyap00z9pwg89yrw5orc8n757fd5.png)
SOlve the resulting expression
![\begin{gathered} M\text{ = 1.9}6*\sqrt[]{(1600)/(92)} \\ M\text{ = 1.96 }*\sqrt[]{17.391} \\ M\text{ = 1.96}*4.17 \\ M\text{ = }8.174 \\ M\text{ }\approx8.2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/stp34yqgnkooy7uohf9gh0e28ru3rl5txc.png)
Hence the the margin of error for the mean, rounded to the nearest tenth is 8.2