Finding the Fourth Proportional to 86.78, 119.72 and 59.10

Step by Step Solution

1. Step 1: Write the proportion equation
   86.78 : 119.72 = 59.10 : x
2. Step 2: Convert to fraction form
   86.78/119.72 = 59.10/x
3. Step 3: Cross multiply
   86.78x = 119.72 × 59.10
4. Step 4: Simplify right side
   86.78x = 7,075.16
5. Step 5: Solve for x
   x = 7,075.16/86.78
6. Step 6: Final answer
   x = 81.53