The 464th Bombing Group flew 187 missions from early May, 1944 until the end of April, 1945. About 40 B-24s were used per mission. The B-24 typically carried a crew of 10 men. The tour of duty was 50 missions. Below is a plot of MACRs filed (planes reported missing in combat) during the time the 464th was stationed in Pantanella Airfield.

In rough numbers: 100/187 = 0.53(53%) = probability of a plane loss (MACR) per mission. 0.53/40 = probability of your plane being lost on any one mission. (1- 0.53/40) raised to the power 50 = 51% = probability of surviving all 50 missions. That is a 49% chance of not surviving. This does not factor in people killed onboard aircraft when an MACR was not issued. Nor does it account for the higher than average MACR rate during the first 3 to 4 months. On the flip side, not all MACRs resulted in fatalities and the plane may have just been lost temporarily. Furthermore, some dangerous missions were actually counted as "two" missions.