Finding the Fourth Proportional to 1,012.72, 1,397.72 and 619.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.72 : 1,397.72 = 619.96 : x
2. Step 2: Convert to fraction form
   1,012.72/1,397.72 = 619.96/x
3. Step 3: Cross multiply
   1,012.72x = 1,397.72 × 619.96
4. Step 4: Simplify right side
   1,012.72x = 866,530.49
5. Step 5: Solve for x
   x = 866,530.49/1,012.72
6. Step 6: Final answer
   x = 855.65