Is net wt of corn flake packets still normal (µ=520 gm, σ=10 gm)?

Is a sample mean wt of 529 gm from 10 packets consistent with µ = 520 gm?

In this simulation, the null hypothesis is that the 10 packets are sampled from a normal (520, 10) population:

Click Accumulate and simulate selection and weighing of 10 corn flake packets from this population between 100 and 200 times. (Hold down the Simulate button.)

A mean weight of 10 packets that is 9 or more grams from the target of 520 gm would be very unlikely if the packing machine was working to specifications, so there is strong evidence that µ is not 520 gm.

Emphasise the general concepts:

Null hypothesis, H0
Each packet has a distribution with µ = 520 gm
Alternative hypothesis, HA
µ ≠ 520 gm
Test statistic
Sample mean of n = 10 packets
P-value
Probability of getting a test statistic as far from 520 gm if H0 is true
Conclusion
A small p-value gives evidence that H0 is not true.

This example is artificial.