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Finding the Fourth Proportional to 691.05, 1,031.54 and 640.29

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Solution

The fourth proportional to 691.05, 1,031.54 and 640.29 is: 955.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.05 : 1,031.54 = 640.29 : x
  2. Step 2: Convert to fraction form
    691.05/1,031.54 = 640.29/x
  3. Step 3: Cross multiply
    691.05x = 1,031.54 × 640.29
  4. Step 4: Simplify right side
    691.05x = 660,484.75
  5. Step 5: Solve for x
    x = 660,484.75/691.05
  6. Step 6: Final answer
    x = 955.77

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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.