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Finding the Fourth Proportional to 687.80, 1,031.46 and 317.45

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Solution

The fourth proportional to 687.80, 1,031.46 and 317.45 is: 476.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.80 : 1,031.46 = 317.45 : x
  2. Step 2: Convert to fraction form
    687.80/1,031.46 = 317.45/x
  3. Step 3: Cross multiply
    687.80x = 1,031.46 × 317.45
  4. Step 4: Simplify right side
    687.80x = 327,434.40
  5. Step 5: Solve for x
    x = 327,434.40/687.80
  6. Step 6: Final answer
    x = 476.06

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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.