Finding the Fourth Proportional to 100.89, 151.12 and 91.80

Step by Step Solution

1. Step 1: Write the proportion equation
   100.89 : 151.12 = 91.80 : x
2. Step 2: Convert to fraction form
   100.89/151.12 = 91.80/x
3. Step 3: Cross multiply
   100.89x = 151.12 × 91.80
4. Step 4: Simplify right side
   100.89x = 13,872.82
5. Step 5: Solve for x
   x = 13,872.82/100.89
6. Step 6: Final answer
   x = 137.50