Finding the Fourth Proportional to 1,390.86, 1,918.35 and 866.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.86 : 1,918.35 = 866.25 : x
2. Step 2: Convert to fraction form
   1,390.86/1,918.35 = 866.25/x
3. Step 3: Cross multiply
   1,390.86x = 1,918.35 × 866.25
4. Step 4: Simplify right side
   1,390.86x = 1,661,770.69
5. Step 5: Solve for x
   x = 1,661,770.69/1,390.86
6. Step 6: Final answer
   x = 1,194.78