Finding the Fourth Proportional to 1,091.46, 1,505.71 and 643.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,091.46 : 1,505.71 = 643.10 : x
2. Step 2: Convert to fraction form
   1,091.46/1,505.71 = 643.10/x
3. Step 3: Cross multiply
   1,091.46x = 1,505.71 × 643.10
4. Step 4: Simplify right side
   1,091.46x = 968,311.36
5. Step 5: Solve for x
   x = 968,311.36/1,091.46
6. Step 6: Final answer
   x = 887.17