Finding the Fourth Proportional to 1,111.60, 1,664.72 and 647.92

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.60 : 1,664.72 = 647.92 : x
2. Step 2: Convert to fraction form
   1,111.60/1,664.72 = 647.92/x
3. Step 3: Cross multiply
   1,111.60x = 1,664.72 × 647.92
4. Step 4: Simplify right side
   1,111.60x = 1,078,605.38
5. Step 5: Solve for x
   x = 1,078,605.38/1,111.60
6. Step 6: Final answer
   x = 970.32