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Finding the Fourth Proportional to 78.10, 107.58 and 65.81

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Solution

The fourth proportional to 78.10, 107.58 and 65.81 is: 90.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.10 : 107.58 = 65.81 : x
  2. Step 2: Convert to fraction form
    78.10/107.58 = 65.81/x
  3. Step 3: Cross multiply
    78.10x = 107.58 × 65.81
  4. Step 4: Simplify right side
    78.10x = 7,079.84
  5. Step 5: Solve for x
    x = 7,079.84/78.10
  6. Step 6: Final answer
    x = 90.66

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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.