Finding the Third Proportional to 390,258 and 851,238

Step by Step Solution

1. Step 1: Write the proportion equation
   390,258 : 851,238 = 851,238 : x
2. Step 2: Convert to fraction form
   390,258/851,238 = 851,238/x
3. Step 3: Cross multiply
   390,258x = 851,238 × 851,238
4. Step 4: Simplify right side
   390,258x = 724,606,132,644
5. Step 5: Solve for x
   x = 724,606,132,644/390,258
6. Step 6: Final answer
   x = 1,856,736.14