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Finding the Fourth Proportional to 78.75, 108.54 and 64.89

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Solution

The fourth proportional to 78.75, 108.54 and 64.89 is: 89.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.75 : 108.54 = 64.89 : x
  2. Step 2: Convert to fraction form
    78.75/108.54 = 64.89/x
  3. Step 3: Cross multiply
    78.75x = 108.54 × 64.89
  4. Step 4: Simplify right side
    78.75x = 7,043.16
  5. Step 5: Solve for x
    x = 7,043.16/78.75
  6. Step 6: Final answer
    x = 89.44

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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.