Finding the Third Proportional to 315,090 and 691,405.50

Step by Step Solution

1. Step 1: Write the proportion equation
   315,090 : 691,405.50 = 691,405.50 : x
2. Step 2: Convert to fraction form
   315,090/691,405.50 = 691,405.50/x
3. Step 3: Cross multiply
   315,090x = 691,405.50 × 691,405.50
4. Step 4: Simplify right side
   315,090x = 478,041,565,430.25
5. Step 5: Solve for x
   x = 478,041,565,430.25/315,090
6. Step 6: Final answer
   x = 1,517,158.80