Finding the Fourth Proportional to 99.90, 149.55 and 82.50

Step by Step Solution

1. Step 1: Write the proportion equation
   99.90 : 149.55 = 82.50 : x
2. Step 2: Convert to fraction form
   99.90/149.55 = 82.50/x
3. Step 3: Cross multiply
   99.90x = 149.55 × 82.50
4. Step 4: Simplify right side
   99.90x = 12,337.88
5. Step 5: Solve for x
   x = 12,337.88/99.90
6. Step 6: Final answer
   x = 123.50