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Finding the Fourth Proportional to 780.74, 1,077.10 and 485.80

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Solution

The fourth proportional to 780.74, 1,077.10 and 485.80 is: 670.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.74 : 1,077.10 = 485.80 : x
  2. Step 2: Convert to fraction form
    780.74/1,077.10 = 485.80/x
  3. Step 3: Cross multiply
    780.74x = 1,077.10 × 485.80
  4. Step 4: Simplify right side
    780.74x = 523,251.27
  5. Step 5: Solve for x
    x = 523,251.27/780.74
  6. Step 6: Final answer
    x = 670.20

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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.