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Finding the Fourth Proportional to 987.12, 1,360.80 and 691.47

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Solution

The fourth proportional to 987.12, 1,360.80 and 691.47 is: 953.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.12 : 1,360.80 = 691.47 : x
  2. Step 2: Convert to fraction form
    987.12/1,360.80 = 691.47/x
  3. Step 3: Cross multiply
    987.12x = 1,360.80 × 691.47
  4. Step 4: Simplify right side
    987.12x = 940,952.38
  5. Step 5: Solve for x
    x = 940,952.38/987.12
  6. Step 6: Final answer
    x = 953.23

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.