Finding the Fourth Proportional to 90.15, 124.41 and 57.39

Step by Step Solution

1. Step 1: Write the proportion equation
   90.15 : 124.41 = 57.39 : x
2. Step 2: Convert to fraction form
   90.15/124.41 = 57.39/x
3. Step 3: Cross multiply
   90.15x = 124.41 × 57.39
4. Step 4: Simplify right side
   90.15x = 7,139.89
5. Step 5: Solve for x
   x = 7,139.89/90.15
6. Step 6: Final answer
   x = 79.20