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Finding the Fourth Proportional to 791.64, 1,186.89 and 421.20

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Solution

The fourth proportional to 791.64, 1,186.89 and 421.20 is: 631.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    791.64 : 1,186.89 = 421.20 : x
  2. Step 2: Convert to fraction form
    791.64/1,186.89 = 421.20/x
  3. Step 3: Cross multiply
    791.64x = 1,186.89 × 421.20
  4. Step 4: Simplify right side
    791.64x = 499,918.07
  5. Step 5: Solve for x
    x = 499,918.07/791.64
  6. Step 6: Final answer
    x = 631.50

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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.