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Finding the Fourth Proportional to 771.15, 1,064.31 and 491.70

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Solution

The fourth proportional to 771.15, 1,064.31 and 491.70 is: 678.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    771.15 : 1,064.31 = 491.70 : x
  2. Step 2: Convert to fraction form
    771.15/1,064.31 = 491.70/x
  3. Step 3: Cross multiply
    771.15x = 1,064.31 × 491.70
  4. Step 4: Simplify right side
    771.15x = 523,323.37
  5. Step 5: Solve for x
    x = 523,323.37/771.15
  6. Step 6: Final answer
    x = 678.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.