Finding the Fourth Proportional to 1,171.72, 1,616.90 and 647.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,171.72 : 1,616.90 = 647.72 : x
2. Step 2: Convert to fraction form
   1,171.72/1,616.90 = 647.72/x
3. Step 3: Cross multiply
   1,171.72x = 1,616.90 × 647.72
4. Step 4: Simplify right side
   1,171.72x = 1,047,298.47
5. Step 5: Solve for x
   x = 1,047,298.47/1,171.72
6. Step 6: Final answer
   x = 893.81