Finding the Fourth Proportional to 139,128.48, 208,531.68 and 64,091.28

Step by Step Solution

1. Step 1: Write the proportion equation
   139,128.48 : 208,531.68 = 64,091.28 : x
2. Step 2: Convert to fraction form
   139,128.48/208,531.68 = 64,091.28/x
3. Step 3: Cross multiply
   139,128.48x = 208,531.68 × 64,091.28
4. Step 4: Simplify right side
   139,128.48x = 13,365,062,291.75
5. Step 5: Solve for x
   x = 13,365,062,291.75/139,128.48
6. Step 6: Final answer
   x = 96,062.73