The Weight of a USB Flash Drive Is 30 Grams $\neq$

Multiple Choice

The weight of a USB flash drive is 30 grams and is normally distributed.Periodically, quality control inspectors at Dallas Flash Drives randomly select a sample of 17 USB flash drives.If the mean weight of the USB flash drives is too heavy or too light the machinery is shut down for adjustment; otherwise, the production process continues.The last sample showed a mean and standard deviation of 31.9 and 1.8 grams, respectively.The null hypothesis is ______.

A) n $\neq$ 17
B) n = 17
C) $\mu$ = 30
D) $\mu$ $\neq$ 30
E) $\mu$ ≥ 34.9