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Finding the Fourth Proportional to 74.85, 103.12 and 56.40

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Solution

The fourth proportional to 74.85, 103.12 and 56.40 is: 77.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.85 : 103.12 = 56.40 : x
  2. Step 2: Convert to fraction form
    74.85/103.12 = 56.40/x
  3. Step 3: Cross multiply
    74.85x = 103.12 × 56.40
  4. Step 4: Simplify right side
    74.85x = 5,815.97
  5. Step 5: Solve for x
    x = 5,815.97/74.85
  6. Step 6: Final answer
    x = 77.70

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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.