Finding the Third Proportional to 251,980 and 390,158

Step by Step Solution

1. Step 1: Write the proportion equation
   251,980 : 390,158 = 390,158 : x
2. Step 2: Convert to fraction form
   251,980/390,158 = 390,158/x
3. Step 3: Cross multiply
   251,980x = 390,158 × 390,158
4. Step 4: Simplify right side
   251,980x = 152,223,264,964
5. Step 5: Solve for x
   x = 152,223,264,964/251,980
6. Step 6: Final answer
   x = 604,108.52