Finding the Fourth Proportional to 139.01, 191.72 and 102.15

Step by Step Solution

1. Step 1: Write the proportion equation
   139.01 : 191.72 = 102.15 : x
2. Step 2: Convert to fraction form
   139.01/191.72 = 102.15/x
3. Step 3: Cross multiply
   139.01x = 191.72 × 102.15
4. Step 4: Simplify right side
   139.01x = 19,583.69
5. Step 5: Solve for x
   x = 19,583.69/139.01
6. Step 6: Final answer
   x = 140.88