Finding the Fourth Proportional to 1,310.72, 1,808.96 and 786.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,310.72 : 1,808.96 = 786.72 : x
2. Step 2: Convert to fraction form
   1,310.72/1,808.96 = 786.72/x
3. Step 3: Cross multiply
   1,310.72x = 1,808.96 × 786.72
4. Step 4: Simplify right side
   1,310.72x = 1,423,145.01
5. Step 5: Solve for x
   x = 1,423,145.01/1,310.72
6. Step 6: Final answer
   x = 1,085.77