Finding the Fourth Proportional to 100.89, 151.61 and 90.18

Step by Step Solution

1. Step 1: Write the proportion equation
   100.89 : 151.61 = 90.18 : x
2. Step 2: Convert to fraction form
   100.89/151.61 = 90.18/x
3. Step 3: Cross multiply
   100.89x = 151.61 × 90.18
4. Step 4: Simplify right side
   100.89x = 13,671.74
5. Step 5: Solve for x
   x = 13,671.74/100.89
6. Step 6: Final answer
   x = 135.51