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Finding the Fourth Proportional to 780.79, 1,170.34 and 415.21

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Solution

The fourth proportional to 780.79, 1,170.34 and 415.21 is: 622.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.79 : 1,170.34 = 415.21 : x
  2. Step 2: Convert to fraction form
    780.79/1,170.34 = 415.21/x
  3. Step 3: Cross multiply
    780.79x = 1,170.34 × 415.21
  4. Step 4: Simplify right side
    780.79x = 485,936.87
  5. Step 5: Solve for x
    x = 485,936.87/780.79
  6. Step 6: Final answer
    x = 622.37

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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.