Finding the Third Proportional to 9,978.75 and 21,408.75

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978.75 : 21,408.75 = 21,408.75 : x
2. Step 2: Convert to fraction form
   9,978.75/21,408.75 = 21,408.75/x
3. Step 3: Cross multiply
   9,978.75x = 21,408.75 × 21,408.75
4. Step 4: Simplify right side
   9,978.75x = 458,334,576.56
5. Step 5: Solve for x
   x = 458,334,576.56/9,978.75
6. Step 6: Final answer
   x = 45,931.06