Nitrites are often added to meat products as preservatives. in a study of the effect of these chemicals on bacteria, the rate of uptake of a radio-labeled amino acid was measured for a number of cultures of bacteria, some growing in a medium to which nitrites had been added. here are the summary statistics from this study.

Nitrites are 307880 115 and control is 30 8112 1250
Let X be nitrate group and let Y  be a control group.
If ∪X-∪Y∠0 then we can say that nitrates decrease the number of amino acids which is taken.
Hypothesis test.
H0:∪X-∪Y=0Vs. Where H1:∪X-∪Y∠0.
Sample for X = 7880 and Y = 8112 and Sx∧2=variance sample for X = 1115∧2 = 1243225 and Sy∧2 = variancesample for Y= 1250∧2 = 1562500. The size of the sample = 30 for both cases.
Test statistics is Z =((7880-8112)-0)/squareroot (1243225/30+1562500/30) = 0.758623)
Value of P = P(Z∠z)
=P(Z∠-0.758623).
Since P-value is greater than the importance of 0.02, we can not reject the null hypothesis. The conclusion is that ∪x-∪y =0 a good example is nitrates does not decrease the number of amino acid which is taken.