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Finding the Fourth Proportional to 71.88, 98.72 and 65.40

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Solution

The fourth proportional to 71.88, 98.72 and 65.40 is: 89.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.88 : 98.72 = 65.40 : x
  2. Step 2: Convert to fraction form
    71.88/98.72 = 65.40/x
  3. Step 3: Cross multiply
    71.88x = 98.72 × 65.40
  4. Step 4: Simplify right side
    71.88x = 6,455.96
  5. Step 5: Solve for x
    x = 6,455.96/71.88
  6. Step 6: Final answer
    x = 89.82

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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.