A study of tire pressure in brand new Toyotas used a sample size of 120 tires and reported a mean of 30.3 psi and a margin or error of plus or minus 1.8 psi with 95% confidence. We may conclude that, with 95% confidence, the mean tire pressure of tires on new Toyota cars is between psi (lower number) and psi (higher number).

28.5 psi and 32.1

Step-by-step explanation:

Since the question already provided the mean (30.3 psi) and the margin of error with confidence of 95% ( + or - 1.8 psi), simply add and subtract the margin of error to the mean value to find the confidence interval:

Lower bound:

L = 30.3 - 1.8 = 28.5

Upper bound:

H = 30.3 + 1.8 = 32.1

Therefore, the mean tire pressure of tires on new Toyota cars is between 28.5 psi and 32.1 psi.