Finding the Third Proportional to 1,290 and 1,978.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290 : 1,978.88 = 1,978.88 : x
2. Step 2: Convert to fraction form
   1,290/1,978.88 = 1,978.88/x
3. Step 3: Cross multiply
   1,290x = 1,978.88 × 1,978.88
4. Step 4: Simplify right side
   1,290x = 3,915,946.27
5. Step 5: Solve for x
   x = 3,915,946.27/1,290
6. Step 6: Final answer
   x = 3,035.62