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Finding the Fourth Proportional to 389.40, 583.70 and 215.80

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Solution

The fourth proportional to 389.40, 583.70 and 215.80 is: 323.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.40 : 583.70 = 215.80 : x
  2. Step 2: Convert to fraction form
    389.40/583.70 = 215.80/x
  3. Step 3: Cross multiply
    389.40x = 583.70 × 215.80
  4. Step 4: Simplify right side
    389.40x = 125,962.46
  5. Step 5: Solve for x
    x = 125,962.46/389.40
  6. Step 6: Final answer
    x = 323.48

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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.