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Finding the Third Proportional to 78 and 87.75

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Solution

The third proportional to 78 and 87.75 is: 98.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    78 : 87.75 = 87.75 : x
  2. Step 2: Convert to fraction form
    78/87.75 = 87.75/x
  3. Step 3: Cross multiply
    78x = 87.75 × 87.75
  4. Step 4: Simplify right side
    78x = 7,700.06
  5. Step 5: Solve for x
    x = 7,700.06/78
  6. Step 6: Final answer
    x = 98.72

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These problems maintain the same ratio (1.13) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.