Finding the Fourth Proportional to 141.82, 212.78 and 90.30

Step by Step Solution

1. Step 1: Write the proportion equation
   141.82 : 212.78 = 90.30 : x
2. Step 2: Convert to fraction form
   141.82/212.78 = 90.30/x
3. Step 3: Cross multiply
   141.82x = 212.78 × 90.30
4. Step 4: Simplify right side
   141.82x = 19,212.52
5. Step 5: Solve for x
   x = 19,212.52/141.82
6. Step 6: Final answer
   x = 135.47