Finding the Fourth Proportional to 42,780.42, 64,117.17 and 20,587.86

Step by Step Solution

1. Step 1: Write the proportion equation
   42,780.42 : 64,117.17 = 20,587.86 : x
2. Step 2: Convert to fraction form
   42,780.42/64,117.17 = 20,587.86/x
3. Step 3: Cross multiply
   42,780.42x = 64,117.17 × 20,587.86
4. Step 4: Simplify right side
   42,780.42x = 1,320,035,319.56
5. Step 5: Solve for x
   x = 1,320,035,319.56/42,780.42
6. Step 6: Final answer
   x = 30,856.06