Finding the Fourth Proportional to 1,307.78, 1,804.72 and 718.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,307.78 : 1,804.72 = 718.30 : x
2. Step 2: Convert to fraction form
   1,307.78/1,804.72 = 718.30/x
3. Step 3: Cross multiply
   1,307.78x = 1,804.72 × 718.30
4. Step 4: Simplify right side
   1,307.78x = 1,296,330.38
5. Step 5: Solve for x
   x = 1,296,330.38/1,307.78
6. Step 6: Final answer
   x = 991.24