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Finding the Fourth Proportional to 28.76, 39.70 and 18.40

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Solution

The fourth proportional to 28.76, 39.70 and 18.40 is: 25.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.76 : 39.70 = 18.40 : x
  2. Step 2: Convert to fraction form
    28.76/39.70 = 18.40/x
  3. Step 3: Cross multiply
    28.76x = 39.70 × 18.40
  4. Step 4: Simplify right side
    28.76x = 730.48
  5. Step 5: Solve for x
    x = 730.48/28.76
  6. Step 6: Final answer
    x = 25.40

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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.