Finding the Third Proportional to 139.50 and 208.13

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 208.13 = 208.13 : x
2. Step 2: Convert to fraction form
   139.50/208.13 = 208.13/x
3. Step 3: Cross multiply
   139.50x = 208.13 × 208.13
4. Step 4: Simplify right side
   139.50x = 43,316.02
5. Step 5: Solve for x
   x = 43,316.02/139.50
6. Step 6: Final answer
   x = 310.51