Finding the Fourth Proportional to 42,886.84, 64,345.40 and 13,312.12

Step by Step Solution

1. Step 1: Write the proportion equation
   42,886.84 : 64,345.40 = 13,312.12 : x
2. Step 2: Convert to fraction form
   42,886.84/64,345.40 = 13,312.12/x
3. Step 3: Cross multiply
   42,886.84x = 64,345.40 × 13,312.12
4. Step 4: Simplify right side
   42,886.84x = 856,573,686.25
5. Step 5: Solve for x
   x = 856,573,686.25/42,886.84
6. Step 6: Final answer
   x = 19,972.88