Finding the Fourth Proportional to 2,087.64, 3,128.09 and 1,917.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,087.64 : 3,128.09 = 1,917.81 : x
2. Step 2: Convert to fraction form
   2,087.64/3,128.09 = 1,917.81/x
3. Step 3: Cross multiply
   2,087.64x = 3,128.09 × 1,917.81
4. Step 4: Simplify right side
   2,087.64x = 5,999,072.69
5. Step 5: Solve for x
   x = 5,999,072.69/2,087.64
6. Step 6: Final answer
   x = 2,873.61