Finding the Fourth Proportional to 104.72, 145.31 and 100.87

Step by Step Solution

1. Step 1: Write the proportion equation
   104.72 : 145.31 = 100.87 : x
2. Step 2: Convert to fraction form
   104.72/145.31 = 100.87/x
3. Step 3: Cross multiply
   104.72x = 145.31 × 100.87
4. Step 4: Simplify right side
   104.72x = 14,656.55
5. Step 5: Solve for x
   x = 14,656.55/104.72
6. Step 6: Final answer
   x = 139.97