**13. Correct. The answer is true**

The test can be formulated as follows

H_{0}:
μ=0.060

H_{a}:
μ ≠ 0.060, so a two-tailed test is required.

Under the H_{0}, T=(`X-
μ)(n-1)^{0.5}/s=(0.063-0.060)*9^{0.5}/0.003=3.

For a two-tailed test at 5% level
of significance, the decision rule is to reject H_{0} if T lies outside
the interval (-t_{0.995} to +t_{0.995 }), which for (10-1)
degrees of freedom is the interval -3.25 to 2.26. Reject H_{0}
otherwise. Since T=3, we reject H_{0} at 5% level. The machine is
therefore in the proper working conditions.