Finding the Fourth Proportional to 1,188.67, 1,636.65 and 978.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.67 : 1,636.65 = 978.18 : x
2. Step 2: Convert to fraction form
   1,188.67/1,636.65 = 978.18/x
3. Step 3: Cross multiply
   1,188.67x = 1,636.65 × 978.18
4. Step 4: Simplify right side
   1,188.67x = 1,600,938.30
5. Step 5: Solve for x
   x = 1,600,938.30/1,188.67
6. Step 6: Final answer
   x = 1,346.83