Finding the Fourth Proportional to 1,315.50, 1,972.86 and 621.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,315.50 : 1,972.86 = 621.78 : x
2. Step 2: Convert to fraction form
   1,315.50/1,972.86 = 621.78/x
3. Step 3: Cross multiply
   1,315.50x = 1,972.86 × 621.78
4. Step 4: Simplify right side
   1,315.50x = 1,226,684.89
5. Step 5: Solve for x
   x = 1,226,684.89/1,315.50
6. Step 6: Final answer
   x = 932.49