Finding the Fourth Proportional to 1,109.89, 1,531.70 and 612.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.89 : 1,531.70 = 612.60 : x
2. Step 2: Convert to fraction form
   1,109.89/1,531.70 = 612.60/x
3. Step 3: Cross multiply
   1,109.89x = 1,531.70 × 612.60
4. Step 4: Simplify right side
   1,109.89x = 938,319.42
5. Step 5: Solve for x
   x = 938,319.42/1,109.89
6. Step 6: Final answer
   x = 845.42