Finding the Fourth Proportional to 42,878, 64,358.60 and 20,706.96

Step by Step Solution

1. Step 1: Write the proportion equation
   42,878 : 64,358.60 = 20,706.96 : x
2. Step 2: Convert to fraction form
   42,878/64,358.60 = 20,706.96/x
3. Step 3: Cross multiply
   42,878x = 64,358.60 × 20,706.96
4. Step 4: Simplify right side
   42,878x = 1,332,670,955.86
5. Step 5: Solve for x
   x = 1,332,670,955.86/42,878
6. Step 6: Final answer
   x = 31,080.53