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Finding the Fourth Proportional to 791.60, 1,187.40 and 278.60

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Solution

The fourth proportional to 791.60, 1,187.40 and 278.60 is: 417.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.60 : 1,187.40 = 278.60 : x
  2. Step 2: Convert to fraction form
    791.60/1,187.40 = 278.60/x
  3. Step 3: Cross multiply
    791.60x = 1,187.40 × 278.60
  4. Step 4: Simplify right side
    791.60x = 330,809.64
  5. Step 5: Solve for x
    x = 330,809.64/791.60
  6. Step 6: Final answer
    x = 417.90

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.