In an environmental impact study for a new airport, the noise level of various jets was measured just seconds after their wheels left the ground. The jets were either wide-bodied or narrow-bodied. The noise levels in decibels are recorded here for 15 wide-body and 12 narrow=body jets. Wide-bodied 109.5 107.3 105.0 117.3 105.4 113.7 121.7 109.2 108.1 106.4 104.6 110.5 110.9 111.0 112.4 Narrow-bodied 131.4 126.8 114.1 126.9 108.2 122.0 106.9 116.3 115.5 111.6 124.5 116.2 (a)Do the two types of jets have different mean noise levels