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Finding the Fourth Proportional to 780.65, 1,077.39 and 485.96

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Solution

The fourth proportional to 780.65, 1,077.39 and 485.96 is: 670.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.65 : 1,077.39 = 485.96 : x
  2. Step 2: Convert to fraction form
    780.65/1,077.39 = 485.96/x
  3. Step 3: Cross multiply
    780.65x = 1,077.39 × 485.96
  4. Step 4: Simplify right side
    780.65x = 523,563.06
  5. Step 5: Solve for x
    x = 523,563.06/780.65
  6. Step 6: Final answer
    x = 670.68

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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.