Use Heron's formula to find the area of the triangle. Round to the nearest square unit. a = 8 inches, b = 13 inches, c = 7 inches

Group of answer choices

39 square inches

23 square inches

21 square inches

41 square inches

James adds two numbers a + b. sally adds the same two numbers but reverse the order b + a what property of addition assures us that james and sally will get the same sum

Aline has a slope of and a y-intercept of –2. what is the x-intercept of the line?

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.