Finding the Fourth Proportional to 78.91, 108.89 and 50.87

Step by Step Solution

1. Step 1: Write the proportion equation
   78.91 : 108.89 = 50.87 : x
2. Step 2: Convert to fraction form
   78.91/108.89 = 50.87/x
3. Step 3: Cross multiply
   78.91x = 108.89 × 50.87
4. Step 4: Simplify right side
   78.91x = 5,539.31
5. Step 5: Solve for x
   x = 5,539.31/78.91
6. Step 6: Final answer
   x = 70.20