Finding the Fourth Proportional to 1,019.88, 1,407.50 and 621.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,019.88 : 1,407.50 = 621.81 : x
2. Step 2: Convert to fraction form
   1,019.88/1,407.50 = 621.81/x
3. Step 3: Cross multiply
   1,019.88x = 1,407.50 × 621.81
4. Step 4: Simplify right side
   1,019.88x = 875,194.47
5. Step 5: Solve for x
   x = 875,194.47/1,019.88
6. Step 6: Final answer
   x = 858.13