PROBLEMS
1. Analysis of
the fat content of samples from a chopped-meat mixture in which the
overall fat content was 15% gave the following results, expressed
as percentages:
23.4 10.4 16.4 19.6 30.4 7.6
For this mixture,
estimate the value of s2, s02,
and sr2, if the samples are 5 g and
the fat and meat are in 0.1 g particles in the mixture.
[0.68 x 10-2 ;
12.8 x 10-2 ; 0.256 x 10-2 ]
2. If it is found
that the mixture in Problem 1 is formed from the initial separate
ingredients of fat and lean meat after mixing for 10 min, estimate
the value of the mixing index after a further 5 min of mixing.
[ 0.966 ; 0.994 ]
3. For a liquid
mixer in which a propeller stirrer, 0.3 m in diameter, is rotating
at 300 rev/min in water estimate the power required to operate the
stirrer. The tank is 0.6 m in diameter.
4. If the same
assembly as in Problem 3 is to be used to stir olive oil estimate
the power needed.
5. A blended
infant feed powder is to include a nutrient supplement, supplied
as a powder similar to the bulk feed, incorporated at 15 parts per
million. The plant is to produce 50 tonnes per day and has powder
mixers with capacities of 3, 0.5 and 0.05 tonnes, which will mix
efficiently down to one-sixth of their nominal capacity. Suggest
a mixing schedule that should lead to the required dispersion of
the supplement.
APPENDICES
)2 + (x2 - 
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