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Finding the Fourth Proportional to 71.78, 98.46 and 65.70

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Solution

The fourth proportional to 71.78, 98.46 and 65.70 is: 90.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.78 : 98.46 = 65.70 : x
  2. Step 2: Convert to fraction form
    71.78/98.46 = 65.70/x
  3. Step 3: Cross multiply
    71.78x = 98.46 × 65.70
  4. Step 4: Simplify right side
    71.78x = 6,468.82
  5. Step 5: Solve for x
    x = 6,468.82/71.78
  6. Step 6: Final answer
    x = 90.13

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.