Finding the Fourth Proportional to 1,010.72, 1,513.20 and 856.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,010.72 : 1,513.20 = 856.64 : x
2. Step 2: Convert to fraction form
   1,010.72/1,513.20 = 856.64/x
3. Step 3: Cross multiply
   1,010.72x = 1,513.20 × 856.64
4. Step 4: Simplify right side
   1,010.72x = 1,296,267.65
5. Step 5: Solve for x
   x = 1,296,267.65/1,010.72
6. Step 6: Final answer
   x = 1,282.52