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Finding the Fourth Proportional to 4.78, 7.21 and 4.72

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Solution

The fourth proportional to 4.78, 7.21 and 4.72 is: 7.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    4.78 : 7.21 = 4.72 : x
  2. Step 2: Convert to fraction form
    4.78/7.21 = 4.72/x
  3. Step 3: Cross multiply
    4.78x = 7.21 × 4.72
  4. Step 4: Simplify right side
    4.78x = 34.03
  5. Step 5: Solve for x
    x = 34.03/4.78
  6. Step 6: Final answer
    x = 7.12

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.