/sci/ - Science & Math

You're both wrong, but your friend is closer. When determining the margin of error, you divide the standard deviation by the square root of the sample size, not the sample size -1. Also, you multiply that by the z-score that corresponds to your give confidence interval. For 90%, that's 1.645. Then you add and subtract that product from the mean.

Heat is the force, temperature is the measurement of heat.