Finding the Fourth Proportional to 42,898.76, 64,345 and 13,315.80

Step by Step Solution

1. Step 1: Write the proportion equation
   42,898.76 : 64,345 = 13,315.80 : x
2. Step 2: Convert to fraction form
   42,898.76/64,345 = 13,315.80/x
3. Step 3: Cross multiply
   42,898.76x = 64,345 × 13,315.80
4. Step 4: Simplify right side
   42,898.76x = 856,805,151
5. Step 5: Solve for x
   x = 856,805,151/42,898.76
6. Step 6: Final answer
   x = 19,972.73