Finding the Fourth Proportional to 1,086.51, 1,499.35 and 644.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.51 : 1,499.35 = 644.15 : x
2. Step 2: Convert to fraction form
   1,086.51/1,499.35 = 644.15/x
3. Step 3: Cross multiply
   1,086.51x = 1,499.35 × 644.15
4. Step 4: Simplify right side
   1,086.51x = 965,803.08
5. Step 5: Solve for x
   x = 965,803.08/1,086.51
6. Step 6: Final answer
   x = 888.90