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Finding the Fourth Proportional to 838.40, 1,257.70 and 405.25

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Solution

The fourth proportional to 838.40, 1,257.70 and 405.25 is: 607.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    838.40 : 1,257.70 = 405.25 : x
  2. Step 2: Convert to fraction form
    838.40/1,257.70 = 405.25/x
  3. Step 3: Cross multiply
    838.40x = 1,257.70 × 405.25
  4. Step 4: Simplify right side
    838.40x = 509,682.93
  5. Step 5: Solve for x
    x = 509,682.93/838.40
  6. Step 6: Final answer
    x = 607.92

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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.