Finding the Fourth Proportional to 1,213.42, 1,680.82 and 1,188.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,213.42 : 1,680.82 = 1,188.80 : x
2. Step 2: Convert to fraction form
   1,213.42/1,680.82 = 1,188.80/x
3. Step 3: Cross multiply
   1,213.42x = 1,680.82 × 1,188.80
4. Step 4: Simplify right side
   1,213.42x = 1,998,158.82
5. Step 5: Solve for x
   x = 1,998,158.82/1,213.42
6. Step 6: Final answer
   x = 1,646.72