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Finding the Fourth Proportional to 786.78, 1,179.36 and 421.07

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Solution

The fourth proportional to 786.78, 1,179.36 and 421.07 is: 631.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.78 : 1,179.36 = 421.07 : x
  2. Step 2: Convert to fraction form
    786.78/1,179.36 = 421.07/x
  3. Step 3: Cross multiply
    786.78x = 1,179.36 × 421.07
  4. Step 4: Simplify right side
    786.78x = 496,587.22
  5. Step 5: Solve for x
    x = 496,587.22/786.78
  6. Step 6: Final answer
    x = 631.16

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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.