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Finding the Fourth Proportional to 42, 63.12 and 31.20

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Solution

The fourth proportional to 42, 63.12 and 31.20 is: 46.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    42 : 63.12 = 31.20 : x
  2. Step 2: Convert to fraction form
    42/63.12 = 31.20/x
  3. Step 3: Cross multiply
    42x = 63.12 × 31.20
  4. Step 4: Simplify right side
    42x = 1,969.34
  5. Step 5: Solve for x
    x = 1,969.34/42
  6. Step 6: Final answer
    x = 46.89

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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.