Im failing.. please help me.. Consider the arithmetic sequence.

-9, -2, 5, 12, . . .

Given that the sequence is represented by the function f(n), what are the values of f(1) and the common difference?

A.
f(1) = -2
Common difference : -7
B.
f(1) = -2
Common difference : 7
C.
f(1) = -9
Common difference : 7
D.
f(1) = -9
Common difference : -7

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.

Simplify. 4+3/7x-2-2/7x a. 2-5/7x b. 6-1/7x c. 2+1/7x d. 6+5/7x

What is the interquartile range of this day at set?