Finding the Fourth Proportional to 90.84, 136.29 and 42.78

Step by Step Solution

1. Step 1: Write the proportion equation
   90.84 : 136.29 = 42.78 : x
2. Step 2: Convert to fraction form
   90.84/136.29 = 42.78/x
3. Step 3: Cross multiply
   90.84x = 136.29 × 42.78
4. Step 4: Simplify right side
   90.84x = 5,830.49
5. Step 5: Solve for x
   x = 5,830.49/90.84
6. Step 6: Final answer
   x = 64.18