Finding the Fourth Proportional to 1,415.90, 2,120.72 and 866.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,415.90 : 2,120.72 = 866.43 : x
2. Step 2: Convert to fraction form
   1,415.90/2,120.72 = 866.43/x
3. Step 3: Cross multiply
   1,415.90x = 2,120.72 × 866.43
4. Step 4: Simplify right side
   1,415.90x = 1,837,451.10
5. Step 5: Solve for x
   x = 1,837,451.10/1,415.90
6. Step 6: Final answer
   x = 1,297.72