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Finding the Fourth Proportional to 420.09, 630.30 and 257.90

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Solution

The fourth proportional to 420.09, 630.30 and 257.90 is: 386.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.09 : 630.30 = 257.90 : x
  2. Step 2: Convert to fraction form
    420.09/630.30 = 257.90/x
  3. Step 3: Cross multiply
    420.09x = 630.30 × 257.90
  4. Step 4: Simplify right side
    420.09x = 162,551.22
  5. Step 5: Solve for x
    x = 162,551.22/420.09
  6. Step 6: Final answer
    x = 386.94

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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.