An engineer has designed a value that will regulate water pressure on an automobile engine. The valve was tested on 160 engines and the mean pressure was 4 lbs/square inch. Assume the standard deviation is known to be 0.9 if the value was designed to produce a mean pressure of 4.2 lbs is there a sufficient evidence at the 0.2 level that the valve performs below specifications? State the bulk and alternative hypotheses for the above scenario

Eight of the truck =m 162 inches
height of the bridge under which vehicles pass = 12 feet 5 inches
                                                                            = (12 * 12) + 5 inches
                                                                            = 144 + 5 inches
                                                                            = 149 inches
we arrived at the above deduction from the fact that 1 feet is equal to 12 inches.
now 
difference in height of the truck and the bridge is = 162 - 149 inches
                                                                              = 13 inches