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Finding the Fourth Proportional to 780.15, 1,171.62 and 415.65

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Solution

The fourth proportional to 780.15, 1,171.62 and 415.65 is: 624.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.15 : 1,171.62 = 415.65 : x
  2. Step 2: Convert to fraction form
    780.15/1,171.62 = 415.65/x
  3. Step 3: Cross multiply
    780.15x = 1,171.62 × 415.65
  4. Step 4: Simplify right side
    780.15x = 486,983.85
  5. Step 5: Solve for x
    x = 486,983.85/780.15
  6. Step 6: Final answer
    x = 624.22

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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.