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Finding the Fourth Proportional to 786.78, 1,179.26 and 421.47

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Solution

The fourth proportional to 786.78, 1,179.26 and 421.47 is: 631.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.78 : 1,179.26 = 421.47 : x
  2. Step 2: Convert to fraction form
    786.78/1,179.26 = 421.47/x
  3. Step 3: Cross multiply
    786.78x = 1,179.26 × 421.47
  4. Step 4: Simplify right side
    786.78x = 497,022.19
  5. Step 5: Solve for x
    x = 497,022.19/786.78
  6. Step 6: Final answer
    x = 631.72

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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.