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Finding the Fourth Proportional to 420.78, 627.20 and 407.52

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Solution

The fourth proportional to 420.78, 627.20 and 407.52 is: 607.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.78 : 627.20 = 407.52 : x
  2. Step 2: Convert to fraction form
    420.78/627.20 = 407.52/x
  3. Step 3: Cross multiply
    420.78x = 627.20 × 407.52
  4. Step 4: Simplify right side
    420.78x = 255,594.51
  5. Step 5: Solve for x
    x = 255,594.51/420.78
  6. Step 6: Final answer
    x = 607.43

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.