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Finding the Fourth Proportional to 690.78, 1,036.14 and 257.91

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Solution

The fourth proportional to 690.78, 1,036.14 and 257.91 is: 386.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.78 : 1,036.14 = 257.91 : x
  2. Step 2: Convert to fraction form
    690.78/1,036.14 = 257.91/x
  3. Step 3: Cross multiply
    690.78x = 1,036.14 × 257.91
  4. Step 4: Simplify right side
    690.78x = 267,227.47
  5. Step 5: Solve for x
    x = 267,227.47/690.78
  6. Step 6: Final answer
    x = 386.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.