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Finding the Fourth Proportional to 779.90, 1,076.45 and 485.39

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Solution

The fourth proportional to 779.90, 1,076.45 and 485.39 is: 669.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    779.90 : 1,076.45 = 485.39 : x
  2. Step 2: Convert to fraction form
    779.90/1,076.45 = 485.39/x
  3. Step 3: Cross multiply
    779.90x = 1,076.45 × 485.39
  4. Step 4: Simplify right side
    779.90x = 522,498.07
  5. Step 5: Solve for x
    x = 522,498.07/779.90
  6. Step 6: Final answer
    x = 669.96

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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.