Finding the Fourth Proportional to 1,111.42, 1,533.72 and 645.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.42 : 1,533.72 = 645.76 : x
2. Step 2: Convert to fraction form
   1,111.42/1,533.72 = 645.76/x
3. Step 3: Cross multiply
   1,111.42x = 1,533.72 × 645.76
4. Step 4: Simplify right side
   1,111.42x = 990,415.03
5. Step 5: Solve for x
   x = 990,415.03/1,111.42
6. Step 6: Final answer
   x = 891.13