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Finding the Fourth Proportional to 691.93, 1,031.48 and 640.09

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Solution

The fourth proportional to 691.93, 1,031.48 and 640.09 is: 954.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.93 : 1,031.48 = 640.09 : x
  2. Step 2: Convert to fraction form
    691.93/1,031.48 = 640.09/x
  3. Step 3: Cross multiply
    691.93x = 1,031.48 × 640.09
  4. Step 4: Simplify right side
    691.93x = 660,241.63
  5. Step 5: Solve for x
    x = 660,241.63/691.93
  6. Step 6: Final answer
    x = 954.20

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.