Test a filling machine using a sample standard deviation

A machine is set to fill bottles with 1000 ml of soy milk. A random sample of 80 filled bottles was taken and the volume of soy milk in each bottle was measured. The sample mean and standard deviation obtained was 997.7 ml and 11.23 ml respectively. Test, at the 4% level of significance, whether the mean volume of soy milk is 1000 ml.5 marks