Answer
There is sufficient evidence to support the claim that there is a loss, on average, in bone mineral with nursing mothers.
Work Step by Step
Mean = $\frac{-4.7 - 2.5 - 4.9 + ... + .2 -2.2 -5.1}{47}$ = -3.5872
z = $\frac{x-u}{o/\sqrt n}$ = $\frac{-3.5872 - 0}{2.5/\sqrt 47}$ = -9.84
P = P(Z < -9.84) = 0