You are concerned that the mean time between failures of the radar system used at the municipal airport is less than the 150 hours claimed by the manufacturer of the system. A random sample of 78 time...

You are concerned that the mean time between failures of the radar system used at the municipal airport is less than the 150 hours claimed by the manufacturer of the system. A random sample of 78 time periods between failures had a mean value of 143.8 hours and a standard deviation of 12.6 hours. Test the manufacturer’s claim against the alternative proposed by yourself at 1 per cent significance level.