Finding the Fourth Proportional to 100.42, 150.81 and 90.34

Step by Step Solution

1. Step 1: Write the proportion equation
   100.42 : 150.81 = 90.34 : x
2. Step 2: Convert to fraction form
   100.42/150.81 = 90.34/x
3. Step 3: Cross multiply
   100.42x = 150.81 × 90.34
4. Step 4: Simplify right side
   100.42x = 13,624.18
5. Step 5: Solve for x
   x = 13,624.18/100.42
6. Step 6: Final answer
   x = 135.67