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Finding the Fourth Proportional to 771.69, 1,065.15 and 491.79

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Solution

The fourth proportional to 771.69, 1,065.15 and 491.79 is: 678.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    771.69 : 1,065.15 = 491.79 : x
  2. Step 2: Convert to fraction form
    771.69/1,065.15 = 491.79/x
  3. Step 3: Cross multiply
    771.69x = 1,065.15 × 491.79
  4. Step 4: Simplify right side
    771.69x = 523,830.12
  5. Step 5: Solve for x
    x = 523,830.12/771.69
  6. Step 6: Final answer
    x = 678.81

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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.