Finding the Fourth Proportional to 2,649.78, 3,972.61 and 1,187.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,649.78 : 3,972.61 = 1,187.91 : x
2. Step 2: Convert to fraction form
   2,649.78/3,972.61 = 1,187.91/x
3. Step 3: Cross multiply
   2,649.78x = 3,972.61 × 1,187.91
4. Step 4: Simplify right side
   2,649.78x = 4,719,100.18
5. Step 5: Solve for x
   x = 4,719,100.18/2,649.78
6. Step 6: Final answer
   x = 1,780.94