Finding the Fourth Proportional to 93.69, 139.86 and 90.72

Step by Step Solution

1. Step 1: Write the proportion equation
   93.69 : 139.86 = 90.72 : x
2. Step 2: Convert to fraction form
   93.69/139.86 = 90.72/x
3. Step 3: Cross multiply
   93.69x = 139.86 × 90.72
4. Step 4: Simplify right side
   93.69x = 12,688.10
5. Step 5: Solve for x
   x = 12,688.10/93.69
6. Step 6: Final answer
   x = 135.43