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Finding the Fourth Proportional to 780.42, 1,077.21 and 485.82

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Solution

The fourth proportional to 780.42, 1,077.21 and 485.82 is: 670.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.42 : 1,077.21 = 485.82 : x
  2. Step 2: Convert to fraction form
    780.42/1,077.21 = 485.82/x
  3. Step 3: Cross multiply
    780.42x = 1,077.21 × 485.82
  4. Step 4: Simplify right side
    780.42x = 523,330.16
  5. Step 5: Solve for x
    x = 523,330.16/780.42
  6. Step 6: Final answer
    x = 670.58

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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.