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Finding the Fourth Proportional to 647.85, 971.90 and 257.78

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Solution

The fourth proportional to 647.85, 971.90 and 257.78 is: 386.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    647.85 : 971.90 = 257.78 : x
  2. Step 2: Convert to fraction form
    647.85/971.90 = 257.78/x
  3. Step 3: Cross multiply
    647.85x = 971.90 × 257.78
  4. Step 4: Simplify right side
    647.85x = 250,536.38
  5. Step 5: Solve for x
    x = 250,536.38/647.85
  6. Step 6: Final answer
    x = 386.72

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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.