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Finding the Fourth Proportional to 51.40, 70.90 and 31.72

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Solution

The fourth proportional to 51.40, 70.90 and 31.72 is: 43.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.40 : 70.90 = 31.72 : x
  2. Step 2: Convert to fraction form
    51.40/70.90 = 31.72/x
  3. Step 3: Cross multiply
    51.40x = 70.90 × 31.72
  4. Step 4: Simplify right side
    51.40x = 2,248.43
  5. Step 5: Solve for x
    x = 2,248.43/51.40
  6. Step 6: Final answer
    x = 43.75

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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.