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Finding the Fourth Proportional to 791.47, 1,088.76 and 643.78

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Solution

The fourth proportional to 791.47, 1,088.76 and 643.78 is: 885.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.47 : 1,088.76 = 643.78 : x
  2. Step 2: Convert to fraction form
    791.47/1,088.76 = 643.78/x
  3. Step 3: Cross multiply
    791.47x = 1,088.76 × 643.78
  4. Step 4: Simplify right side
    791.47x = 700,921.91
  5. Step 5: Solve for x
    x = 700,921.91/791.47
  6. Step 6: Final answer
    x = 885.60

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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.