Finding the Fourth Proportional to 1,136.15, 1,567.86 and 638.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,136.15 : 1,567.86 = 638.78 : x
2. Step 2: Convert to fraction form
   1,136.15/1,567.86 = 638.78/x
3. Step 3: Cross multiply
   1,136.15x = 1,567.86 × 638.78
4. Step 4: Simplify right side
   1,136.15x = 1,001,519.79
5. Step 5: Solve for x
   x = 1,001,519.79/1,136.15
6. Step 6: Final answer
   x = 881.50