Finding the Fourth Proportional to 78.38, 108.18 and 50.71

Step by Step Solution

1. Step 1: Write the proportion equation
   78.38 : 108.18 = 50.71 : x
2. Step 2: Convert to fraction form
   78.38/108.18 = 50.71/x
3. Step 3: Cross multiply
   78.38x = 108.18 × 50.71
4. Step 4: Simplify right side
   78.38x = 5,485.81
5. Step 5: Solve for x
   x = 5,485.81/78.38
6. Step 6: Final answer
   x = 69.99