A scale says that it's readings are accurate to within 1%, meaning that when an object is weighed using that scale, the reading will have an error of at most 1%.

Gillian puts a math textbook on a scale, and the scale reads 1,999.8 grams. What is
the difference between the maximum and minimum possible values for the textbook's
actual weight?

(26.2252 ; 27.3748)

Step-by-step explanation:

The confidence interval is given by :

x ± Margin of error

The margin of error = Zcritical * (σ/√(n))

σ = 7.5 ; n = 654

Zcritical = Zα/2 = 1.96

The margin of error = 1.96 * (7.5/√654) = 0.5748

The confidence interval :

Upper boundary = 26.8 + 0.5748 = 27.3748

Lower boundary = 26.8 - 0.5748 = 26.2252

(26.2252 ; 27.3748)

We are 95% confident that the mean BMI of the entire population will fall in between (26.2252 ; 27.3748)