Finding the Fourth Proportional to 90.42, 124.82 and 57.72

Step by Step Solution

1. Step 1: Write the proportion equation
   90.42 : 124.82 = 57.72 : x
2. Step 2: Convert to fraction form
   90.42/124.82 = 57.72/x
3. Step 3: Cross multiply
   90.42x = 124.82 × 57.72
4. Step 4: Simplify right side
   90.42x = 7,204.44
5. Step 5: Solve for x
   x = 7,204.44/90.42
6. Step 6: Final answer
   x = 79.68