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Finding the Fourth Proportional to 691.80, 1,031.50 and 679.50

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Solution

The fourth proportional to 691.80, 1,031.50 and 679.50 is: 1,013.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.80 : 1,031.50 = 679.50 : x
  2. Step 2: Convert to fraction form
    691.80/1,031.50 = 679.50/x
  3. Step 3: Cross multiply
    691.80x = 1,031.50 × 679.50
  4. Step 4: Simplify right side
    691.80x = 700,904.25
  5. Step 5: Solve for x
    x = 700,904.25/691.80
  6. Step 6: Final answer
    x = 1,013.16

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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.