Finding the Fourth Proportional to 1,312.42, 1,966.20 and 661.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,312.42 : 1,966.20 = 661.59 : x
2. Step 2: Convert to fraction form
   1,312.42/1,966.20 = 661.59/x
3. Step 3: Cross multiply
   1,312.42x = 1,966.20 × 661.59
4. Step 4: Simplify right side
   1,312.42x = 1,300,818.26
5. Step 5: Solve for x
   x = 1,300,818.26/1,312.42
6. Step 6: Final answer
   x = 991.16