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Finding the Fourth Proportional to 78.74, 117.89 and 65.78

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Solution

The fourth proportional to 78.74, 117.89 and 65.78 is: 98.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.74 : 117.89 = 65.78 : x
  2. Step 2: Convert to fraction form
    78.74/117.89 = 65.78/x
  3. Step 3: Cross multiply
    78.74x = 117.89 × 65.78
  4. Step 4: Simplify right side
    78.74x = 7,754.80
  5. Step 5: Solve for x
    x = 7,754.80/78.74
  6. Step 6: Final answer
    x = 98.49

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.