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Finding the Fourth Proportional to 686.90, 1,030.76 and 661.80

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Solution

The fourth proportional to 686.90, 1,030.76 and 661.80 is: 993.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.90 : 1,030.76 = 661.80 : x
  2. Step 2: Convert to fraction form
    686.90/1,030.76 = 661.80/x
  3. Step 3: Cross multiply
    686.90x = 1,030.76 × 661.80
  4. Step 4: Simplify right side
    686.90x = 682,156.97
  5. Step 5: Solve for x
    x = 682,156.97/686.90
  6. Step 6: Final answer
    x = 993.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.