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Finding the Fourth Proportional to 78.98, 108.81 and 65.81

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Solution

The fourth proportional to 78.98, 108.81 and 65.81 is: 90.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.98 : 108.81 = 65.81 : x
  2. Step 2: Convert to fraction form
    78.98/108.81 = 65.81/x
  3. Step 3: Cross multiply
    78.98x = 108.81 × 65.81
  4. Step 4: Simplify right side
    78.98x = 7,161.06
  5. Step 5: Solve for x
    x = 7,161.06/78.98
  6. Step 6: Final answer
    x = 90.68

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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.