Finding the Third Proportional to 1,216.90 and 1,353.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.90 : 1,353.59 = 1,353.59 : x
2. Step 2: Convert to fraction form
   1,216.90/1,353.59 = 1,353.59/x
3. Step 3: Cross multiply
   1,216.90x = 1,353.59 × 1,353.59
4. Step 4: Simplify right side
   1,216.90x = 1,832,194.89
5. Step 5: Solve for x
   x = 1,832,194.89/1,216.90
6. Step 6: Final answer
   x = 1,505.63