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Finding the Fourth Proportional to 639.48, 881.86 and 491.80

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Solution

The fourth proportional to 639.48, 881.86 and 491.80 is: 678.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.48 : 881.86 = 491.80 : x
  2. Step 2: Convert to fraction form
    639.48/881.86 = 491.80/x
  3. Step 3: Cross multiply
    639.48x = 881.86 × 491.80
  4. Step 4: Simplify right side
    639.48x = 433,698.75
  5. Step 5: Solve for x
    x = 433,698.75/639.48
  6. Step 6: Final answer
    x = 678.21

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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.