Finding the Fourth Proportional to 1,208.50, 1,666.20 and 1,031.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,208.50 : 1,666.20 = 1,031.10 : x
2. Step 2: Convert to fraction form
   1,208.50/1,666.20 = 1,031.10/x
3. Step 3: Cross multiply
   1,208.50x = 1,666.20 × 1,031.10
4. Step 4: Simplify right side
   1,208.50x = 1,718,018.82
5. Step 5: Solve for x
   x = 1,718,018.82/1,208.50
6. Step 6: Final answer
   x = 1,421.61