Finding the Fourth Proportional to 1,139.78, 1,700.72 and 1,070.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.78 : 1,700.72 = 1,070.12 : x
2. Step 2: Convert to fraction form
   1,139.78/1,700.72 = 1,070.12/x
3. Step 3: Cross multiply
   1,139.78x = 1,700.72 × 1,070.12
4. Step 4: Simplify right side
   1,139.78x = 1,819,974.49
5. Step 5: Solve for x
   x = 1,819,974.49/1,139.78
6. Step 6: Final answer
   x = 1,596.78