Question

Please use data from #9 to answer #10

9. A company that manufactures bicycles
receives steel rods in large shipments from a
supplier. From past experience, the manager
knows that σ = 0.12 inches and that the lengths
are approximately normally distributed. He
takes a random sample of 12 rods. The lengths
of the sampled rods are as follows:

12.12 11.90 11.94 12.05 12.07 11.97
12.01 12.08 12.05 12.12 12.14 11.15

The manager wants to estimate the mean length
of the latest shipment of rods using a 99 percent
confidence interval. Help this manager construct
a confidence interval and interpret it.

10. With reference to problem 9 above, the
company needs rods with a length of 12 inches
in order to assemble the bikes properly. Because
too-large and too-small rods are unsuitable,
shipments not meeting the requirement are sent
back to the supplier. Help this manager
determine whether the shipment should be
accepted or rejected. Perform a hypothesis
testing with α = 10% .

Answer 1