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Finding the Fourth Proportional to 42.91, 64.40 and 31.45

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Solution

The fourth proportional to 42.91, 64.40 and 31.45 is: 47.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.91 : 64.40 = 31.45 : x
  2. Step 2: Convert to fraction form
    42.91/64.40 = 31.45/x
  3. Step 3: Cross multiply
    42.91x = 64.40 × 31.45
  4. Step 4: Simplify right side
    42.91x = 2,025.38
  5. Step 5: Solve for x
    x = 2,025.38/42.91
  6. Step 6: Final answer
    x = 47.20

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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.