Finding the Fourth Proportional to 1,086.74, 1,499.90 and 620.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.74 : 1,499.90 = 620.99 : x
2. Step 2: Convert to fraction form
   1,086.74/1,499.90 = 620.99/x
3. Step 3: Cross multiply
   1,086.74x = 1,499.90 × 620.99
4. Step 4: Simplify right side
   1,086.74x = 931,422.90
5. Step 5: Solve for x
   x = 931,422.90/1,086.74
6. Step 6: Final answer
   x = 857.08