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Finding the Fourth Proportional to 75.12, 103.72 and 61.40

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Solution

The fourth proportional to 75.12, 103.72 and 61.40 is: 84.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    75.12 : 103.72 = 61.40 : x
  2. Step 2: Convert to fraction form
    75.12/103.72 = 61.40/x
  3. Step 3: Cross multiply
    75.12x = 103.72 × 61.40
  4. Step 4: Simplify right side
    75.12x = 6,368.41
  5. Step 5: Solve for x
    x = 6,368.41/75.12
  6. Step 6: Final answer
    x = 84.78

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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.