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Finding the Fourth Proportional to 70.78, 97.76 and 65

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Solution

The fourth proportional to 70.78, 97.76 and 65 is: 89.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.78 : 97.76 = 65 : x
  2. Step 2: Convert to fraction form
    70.78/97.76 = 65/x
  3. Step 3: Cross multiply
    70.78x = 97.76 × 65
  4. Step 4: Simplify right side
    70.78x = 6,354.40
  5. Step 5: Solve for x
    x = 6,354.40/70.78
  6. Step 6: Final answer
    x = 89.78

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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.