Finding the Fourth Proportional to 1,012.98, 1,517.76 and 427.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.98 : 1,517.76 = 427.50 : x
2. Step 2: Convert to fraction form
   1,012.98/1,517.76 = 427.50/x
3. Step 3: Cross multiply
   1,012.98x = 1,517.76 × 427.50
4. Step 4: Simplify right side
   1,012.98x = 648,842.40
5. Step 5: Solve for x
   x = 648,842.40/1,012.98
6. Step 6: Final answer
   x = 640.53