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Finding the Fourth Proportional to 78.51, 108.57 and 69.89

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Solution

The fourth proportional to 78.51, 108.57 and 69.89 is: 96.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.51 : 108.57 = 69.89 : x
  2. Step 2: Convert to fraction form
    78.51/108.57 = 69.89/x
  3. Step 3: Cross multiply
    78.51x = 108.57 × 69.89
  4. Step 4: Simplify right side
    78.51x = 7,587.96
  5. Step 5: Solve for x
    x = 7,587.96/78.51
  6. Step 6: Final answer
    x = 96.65

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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.