Finding the Third Proportional to 99.78 and 145.78

Step by Step Solution

1. Step 1: Write the proportion equation
   99.78 : 145.78 = 145.78 : x
2. Step 2: Convert to fraction form
   99.78/145.78 = 145.78/x
3. Step 3: Cross multiply
   99.78x = 145.78 × 145.78
4. Step 4: Simplify right side
   99.78x = 21,252.17
5. Step 5: Solve for x
   x = 21,252.17/99.78
6. Step 6: Final answer
   x = 212.99