Finding the Fourth Proportional to 90.42, 124.86 and 72.12

Step by Step Solution

1. Step 1: Write the proportion equation
   90.42 : 124.86 = 72.12 : x
2. Step 2: Convert to fraction form
   90.42/124.86 = 72.12/x
3. Step 3: Cross multiply
   90.42x = 124.86 × 72.12
4. Step 4: Simplify right side
   90.42x = 9,004.90
5. Step 5: Solve for x
   x = 9,004.90/90.42
6. Step 6: Final answer
   x = 99.59