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Finding the Fourth Proportional to 686.80, 1,030.20 and 653.20

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Solution

The fourth proportional to 686.80, 1,030.20 and 653.20 is: 979.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.80 : 1,030.20 = 653.20 : x
  2. Step 2: Convert to fraction form
    686.80/1,030.20 = 653.20/x
  3. Step 3: Cross multiply
    686.80x = 1,030.20 × 653.20
  4. Step 4: Simplify right side
    686.80x = 672,926.64
  5. Step 5: Solve for x
    x = 672,926.64/686.80
  6. Step 6: Final answer
    x = 979.80

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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.