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Finding the Fourth Proportional to 862.19, 1,189.78 and 469.20

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Solution

The fourth proportional to 862.19, 1,189.78 and 469.20 is: 647.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.19 : 1,189.78 = 469.20 : x
  2. Step 2: Convert to fraction form
    862.19/1,189.78 = 469.20/x
  3. Step 3: Cross multiply
    862.19x = 1,189.78 × 469.20
  4. Step 4: Simplify right side
    862.19x = 558,244.78
  5. Step 5: Solve for x
    x = 558,244.78/862.19
  6. Step 6: Final answer
    x = 647.47

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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.