An inclned manometer with indicating leg at 30 is to be used at 20 to measure an air pressure of nominal magnitude of 100 relative to ambient. "Unity" oil (S = 1)is to be used.The specific weight of the oil is 9770 at 20,the angle of inclnation can be set to within 1 using a bubble level, and the manometer resolution is 1 mm with a manometer zero error equal to its interpolation error. Estimate the uncertainty in indicated differential pressure at the design stage.