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Finding the Fourth Proportional to 42.74, 64.12 and 18.70

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Solution

The fourth proportional to 42.74, 64.12 and 18.70 is: 28.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.74 : 64.12 = 18.70 : x
  2. Step 2: Convert to fraction form
    42.74/64.12 = 18.70/x
  3. Step 3: Cross multiply
    42.74x = 64.12 × 18.70
  4. Step 4: Simplify right side
    42.74x = 1,199.04
  5. Step 5: Solve for x
    x = 1,199.04/42.74
  6. Step 6: Final answer
    x = 28.05

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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.