Finding the Fourth Proportional to 1,180.72, 1,770.28 and 856.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,180.72 : 1,770.28 = 856.72 : x
2. Step 2: Convert to fraction form
   1,180.72/1,770.28 = 856.72/x
3. Step 3: Cross multiply
   1,180.72x = 1,770.28 × 856.72
4. Step 4: Simplify right side
   1,180.72x = 1,516,634.28
5. Step 5: Solve for x
   x = 1,516,634.28/1,180.72
6. Step 6: Final answer
   x = 1,284.50