Finding the Fourth Proportional to 111.50, 153.90 and 64.88

Step by Step Solution

1. Step 1: Write the proportion equation
   111.50 : 153.90 = 64.88 : x
2. Step 2: Convert to fraction form
   111.50/153.90 = 64.88/x
3. Step 3: Cross multiply
   111.50x = 153.90 × 64.88
4. Step 4: Simplify right side
   111.50x = 9,985.42
5. Step 5: Solve for x
   x = 9,985.42/111.50
6. Step 6: Final answer
   x = 89.56