Finding the Fourth Proportional to 1,036.48, 1,430.18 and 643.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,036.48 : 1,430.18 = 643.50 : x
2. Step 2: Convert to fraction form
   1,036.48/1,430.18 = 643.50/x
3. Step 3: Cross multiply
   1,036.48x = 1,430.18 × 643.50
4. Step 4: Simplify right side
   1,036.48x = 920,320.83
5. Step 5: Solve for x
   x = 920,320.83/1,036.48
6. Step 6: Final answer
   x = 887.93