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Finding the Fourth Proportional to 78.65, 117.40 and 69.56

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Solution

The fourth proportional to 78.65, 117.40 and 69.56 is: 103.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.65 : 117.40 = 69.56 : x
  2. Step 2: Convert to fraction form
    78.65/117.40 = 69.56/x
  3. Step 3: Cross multiply
    78.65x = 117.40 × 69.56
  4. Step 4: Simplify right side
    78.65x = 8,166.34
  5. Step 5: Solve for x
    x = 8,166.34/78.65
  6. Step 6: Final answer
    x = 103.83

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.