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Finding the Fourth Proportional to 542.40, 811.98 and 420

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Solution

The fourth proportional to 542.40, 811.98 and 420 is: 628.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    542.40 : 811.98 = 420 : x
  2. Step 2: Convert to fraction form
    542.40/811.98 = 420/x
  3. Step 3: Cross multiply
    542.40x = 811.98 × 420
  4. Step 4: Simplify right side
    542.40x = 341,031.60
  5. Step 5: Solve for x
    x = 341,031.60/542.40
  6. Step 6: Final answer
    x = 628.75

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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.