Finding the Fourth Proportional to 89.76, 123.80 and 83.20

Step by Step Solution

1. Step 1: Write the proportion equation
   89.76 : 123.80 = 83.20 : x
2. Step 2: Convert to fraction form
   89.76/123.80 = 83.20/x
3. Step 3: Cross multiply
   89.76x = 123.80 × 83.20
4. Step 4: Simplify right side
   89.76x = 10,300.16
5. Step 5: Solve for x
   x = 10,300.16/89.76
6. Step 6: Final answer
   x = 114.75