Finding the Fourth Proportional to 1,308.17, 1,805.28 and 718.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,308.17 : 1,805.28 = 718.72 : x
2. Step 2: Convert to fraction form
   1,308.17/1,805.28 = 718.72/x
3. Step 3: Cross multiply
   1,308.17x = 1,805.28 × 718.72
4. Step 4: Simplify right side
   1,308.17x = 1,297,490.84
5. Step 5: Solve for x
   x = 1,297,490.84/1,308.17
6. Step 6: Final answer
   x = 991.84