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Finding the Fourth Proportional to 858.52, 1,287.82 and 420.18

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Solution

The fourth proportional to 858.52, 1,287.82 and 420.18 is: 630.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.52 : 1,287.82 = 420.18 : x
  2. Step 2: Convert to fraction form
    858.52/1,287.82 = 420.18/x
  3. Step 3: Cross multiply
    858.52x = 1,287.82 × 420.18
  4. Step 4: Simplify right side
    858.52x = 541,116.21
  5. Step 5: Solve for x
    x = 541,116.21/858.52
  6. Step 6: Final answer
    x = 630.29

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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.