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Finding the Fourth Proportional to 386.40, 579.50 and 139.58

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Solution

The fourth proportional to 386.40, 579.50 and 139.58 is: 209.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.40 : 579.50 = 139.58 : x
  2. Step 2: Convert to fraction form
    386.40/579.50 = 139.58/x
  3. Step 3: Cross multiply
    386.40x = 579.50 × 139.58
  4. Step 4: Simplify right side
    386.40x = 80,886.61
  5. Step 5: Solve for x
    x = 80,886.61/386.40
  6. Step 6: Final answer
    x = 209.33

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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.