Finding the Fourth Proportional to 99.90, 149.88 and 42.09

Step by Step Solution

1. Step 1: Write the proportion equation
   99.90 : 149.88 = 42.09 : x
2. Step 2: Convert to fraction form
   99.90/149.88 = 42.09/x
3. Step 3: Cross multiply
   99.90x = 149.88 × 42.09
4. Step 4: Simplify right side
   99.90x = 6,308.82
5. Step 5: Solve for x
   x = 6,308.82/99.90
6. Step 6: Final answer
   x = 63.15