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Finding the Fourth Proportional to 71.78, 99 and 56.21

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Solution

The fourth proportional to 71.78, 99 and 56.21 is: 77.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.78 : 99 = 56.21 : x
  2. Step 2: Convert to fraction form
    71.78/99 = 56.21/x
  3. Step 3: Cross multiply
    71.78x = 99 × 56.21
  4. Step 4: Simplify right side
    71.78x = 5,564.79
  5. Step 5: Solve for x
    x = 5,564.79/71.78
  6. Step 6: Final answer
    x = 77.53

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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.