Finding the Fourth Proportional to 1,086.64, 1,499.52 and 620.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.64 : 1,499.52 = 620.90 : x
2. Step 2: Convert to fraction form
   1,086.64/1,499.52 = 620.90/x
3. Step 3: Cross multiply
   1,086.64x = 1,499.52 × 620.90
4. Step 4: Simplify right side
   1,086.64x = 931,051.97
5. Step 5: Solve for x
   x = 931,051.97/1,086.64
6. Step 6: Final answer
   x = 856.82