In: Statistics and Probability
A manufacturer of breakfast cereal makes two claims concerning
the
weight of the packets they produce. The manufacturer claims
that
a) The mean is 200g
b) The variance is 0.8g2.
Answer the following questions.
1. To investigate the claims, the weight of a sample of
packets
produced in a given shift was measured. The values found are
listed in part (a) of ‘Dataset’, with grams (g) as the unit
of measurement. Carry out appropriate statistical tests on claims
(a)
and (b).
2. Several weeks later, a smaller sample of packets as taken and
their
weight was measured; the data is listed in part (b) of
‘Dataset’, with grams (g) as the unit of measurement. Use
this
data to construct confidence intervals for the mean and variance
of
the variable ‘W’, the weight of a packet of cereal.
3. Identify any issues with adding the second set of data to the
first
and ‘updating’ the results of part 1.
Part (a) | |||||
208.06 | 201.19 | 205.61 | 200.88 | 194.48 | 196.53 |
206.21 | 200.82 | 205.86 | 199.82 | 196.54 | 198.60 |
204.72 | 197.88 | 204.67 | 200.72 | 199.07 | 195.57 |
202.28 | 197.28 | 201.27 | 197.73 | 195.89 | 198.16 |
202.63 | 198.48 | 198.34 | 201.29 | 194.63 | 199.24 |
204.83 | 196.14 | 201.12 | 198.10 | 191.65 | 198.96 |
206.69 | 198.17 | 203.46 | 196.92 | 195.06 | 199.44 |
Part (b) | |||||
207.94 | 199.36 | 201.16 | 193.67 | 196.07 | 202.28 |
204.64 | 202.77 | 202.33 | 192.26 | 199.62 | 202.93 |
2. 95% Confidence Interval for the mean of the packets of part (b) is:
Part B | |
count | 12 |
mean | 200.4192 |
sample standard deviation | 4.5394 |
sample variance | 20.6064 |
minimum | 192.26 |
maximum | 207.94 |
range | 15.68 |
confidence interval 95.% lower | 197.8508 |
confidence interval 95.% upper | 202.9875 |
margin of error | 2.5684 |
z | 1.96 |
3. As we can see that the mean for the part (b) is more than 200g and if it is added to the data of part (a), it can change the mean of the part (a) which violates its satisfiability of mean of 200g.