Finding the Fourth Proportional to 1,706.16, 2,560.20 and 840.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,706.16 : 2,560.20 = 840.72 : x
2. Step 2: Convert to fraction form
   1,706.16/2,560.20 = 840.72/x
3. Step 3: Cross multiply
   1,706.16x = 2,560.20 × 840.72
4. Step 4: Simplify right side
   1,706.16x = 2,152,411.34
5. Step 5: Solve for x
   x = 2,152,411.34/1,706.16
6. Step 6: Final answer
   x = 1,261.55