Finding the Fourth Proportional to 1,310.47, 1,808.50 and 721.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,310.47 : 1,808.50 = 721.05 : x
2. Step 2: Convert to fraction form
   1,310.47/1,808.50 = 721.05/x
3. Step 3: Cross multiply
   1,310.47x = 1,808.50 × 721.05
4. Step 4: Simplify right side
   1,310.47x = 1,304,015.32
5. Step 5: Solve for x
   x = 1,304,015.32/1,310.47
6. Step 6: Final answer
   x = 995.07