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Finding the Fourth Proportional to 47.80, 66 and 28.40

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Solution

The fourth proportional to 47.80, 66 and 28.40 is: 39.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.80 : 66 = 28.40 : x
  2. Step 2: Convert to fraction form
    47.80/66 = 28.40/x
  3. Step 3: Cross multiply
    47.80x = 66 × 28.40
  4. Step 4: Simplify right side
    47.80x = 1,874.40
  5. Step 5: Solve for x
    x = 1,874.40/47.80
  6. Step 6: Final answer
    x = 39.21

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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.