Finding the Fourth Proportional to 1,388.89, 2,081.67 and 647.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.89 : 2,081.67 = 647.50 : x
2. Step 2: Convert to fraction form
   1,388.89/2,081.67 = 647.50/x
3. Step 3: Cross multiply
   1,388.89x = 2,081.67 × 647.50
4. Step 4: Simplify right side
   1,388.89x = 1,347,881.33
5. Step 5: Solve for x
   x = 1,347,881.33/1,388.89
6. Step 6: Final answer
   x = 970.47