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Finding the Fourth Proportional to 780.57, 1,171.20 and 415.28

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Solution

The fourth proportional to 780.57, 1,171.20 and 415.28 is: 623.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.57 : 1,171.20 = 415.28 : x
  2. Step 2: Convert to fraction form
    780.57/1,171.20 = 415.28/x
  3. Step 3: Cross multiply
    780.57x = 1,171.20 × 415.28
  4. Step 4: Simplify right side
    780.57x = 486,370.08
  5. Step 5: Solve for x
    x = 486,370.08/780.57
  6. Step 6: Final answer
    x = 623.10

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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.