Finding the Fourth Proportional to 1,615.72, 2,229.72 and 917.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,615.72 : 2,229.72 = 917.10 : x
2. Step 2: Convert to fraction form
   1,615.72/2,229.72 = 917.10/x
3. Step 3: Cross multiply
   1,615.72x = 2,229.72 × 917.10
4. Step 4: Simplify right side
   1,615.72x = 2,044,876.21
5. Step 5: Solve for x
   x = 2,044,876.21/1,615.72
6. Step 6: Final answer
   x = 1,265.61