Finding the Fourth Proportional to 2,117.56, 2,920.43 and 1,278.09

Step by Step Solution

1. Step 1: Write the proportion equation
   2,117.56 : 2,920.43 = 1,278.09 : x
2. Step 2: Convert to fraction form
   2,117.56/2,920.43 = 1,278.09/x
3. Step 3: Cross multiply
   2,117.56x = 2,920.43 × 1,278.09
4. Step 4: Simplify right side
   2,117.56x = 3,732,572.38
5. Step 5: Solve for x
   x = 3,732,572.38/2,117.56
6. Step 6: Final answer
   x = 1,762.68