Finding the Fourth Proportional to 978.57, 1,346.76 and 899.91

Step by Step Solution

1. Step 1: Write the proportion equation
   978.57 : 1,346.76 = 899.91 : x
2. Step 2: Convert to fraction form
   978.57/1,346.76 = 899.91/x
3. Step 3: Cross multiply
   978.57x = 1,346.76 × 899.91
4. Step 4: Simplify right side
   978.57x = 1,211,962.79
5. Step 5: Solve for x
   x = 1,211,962.79/978.57
6. Step 6: Final answer
   x = 1,238.50