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Finding the Fourth Proportional to 691.50, 1,031.15 and 641.28

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Solution

The fourth proportional to 691.50, 1,031.15 and 641.28 is: 956.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.50 : 1,031.15 = 641.28 : x
  2. Step 2: Convert to fraction form
    691.50/1,031.15 = 641.28/x
  3. Step 3: Cross multiply
    691.50x = 1,031.15 × 641.28
  4. Step 4: Simplify right side
    691.50x = 661,252.67
  5. Step 5: Solve for x
    x = 661,252.67/691.50
  6. Step 6: Final answer
    x = 956.26

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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.