Finding the Fourth Proportional to 89.91, 124.03 and 57.15

Step by Step Solution

1. Step 1: Write the proportion equation
   89.91 : 124.03 = 57.15 : x
2. Step 2: Convert to fraction form
   89.91/124.03 = 57.15/x
3. Step 3: Cross multiply
   89.91x = 124.03 × 57.15
4. Step 4: Simplify right side
   89.91x = 7,088.31
5. Step 5: Solve for x
   x = 7,088.31/89.91
6. Step 6: Final answer
   x = 78.84