Finding the Fourth Proportional to 1,242.78, 1,714.76 and 718.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,242.78 : 1,714.76 = 718.72 : x
2. Step 2: Convert to fraction form
   1,242.78/1,714.76 = 718.72/x
3. Step 3: Cross multiply
   1,242.78x = 1,714.76 × 718.72
4. Step 4: Simplify right side
   1,242.78x = 1,232,432.31
5. Step 5: Solve for x
   x = 1,232,432.31/1,242.78
6. Step 6: Final answer
   x = 991.67