Finding the Fourth Proportional to 1,111.78, 1,665.37 and 648.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.78 : 1,665.37 = 648.16 : x
2. Step 2: Convert to fraction form
   1,111.78/1,665.37 = 648.16/x
3. Step 3: Cross multiply
   1,111.78x = 1,665.37 × 648.16
4. Step 4: Simplify right side
   1,111.78x = 1,079,415.58
5. Step 5: Solve for x
   x = 1,079,415.58/1,111.78
6. Step 6: Final answer
   x = 970.89